The Mark of Athena

''This article is about the book. You may be looking for The Mark of Athena (coin).''

The Mark of Athena is the third installment of The Heroes of Olympus series. It was released on October 2, 2012. The book continues where The Son of Neptune left off, beginning shortly before The Son of Neptune ended, and is told from the points-of-view of Annabeth Chase, Leo Valdez, Piper McLean, and Percy Jackson.

Development
Rick Riordan has been working on The Mark of Athena since the completion of The Son of Neptune. While Amazon.com released information on the book, including page numbers, Rick mentioned that the book wasn't finished yet.

During his tour to promote the last of The Kane Chronicles books, titled The Serpent's Shadow, Rick read part of the first chapter of The Mark of Athena. There, it is revealed that Annabeth Chase is one of the narrators. The cover and full first chapter were released on June 1 on the Disney Heroes of Olympus website.

On September 27, Rick Riordan confirmed that there would be first US printing of 3.5 million copies.

Uniting the Camps
While getting ready to land at Camp Jupiter, Annabeth Chase prepares by making sure the back-up plans are ready in case something goes wrong, as well as the back-ups to the back-up plans. While Leo Valdez is flying the Argo II with a control system that involved Wii remotes, a dubstep sound board, a keyboard, and a monitor, Annabeth tries to keep Gleeson Hedge from attacking the first thing he sees by making him watch reruns of mixed martial arts championships in his cabin. Jason Grace prepares by putting on a purple toga over his orange Camp Half-Blood t-shirt and Piper McLean practices her lines for the landing. As Annabeth watches Jason, she wonders if this could all be a trap, as she was still a bit distrusting of Jason because he seems too perfect. She is also reminded of how much she misses Percy Jackson (her boyfriend) every time she looks at Jason.

Annabeth also mentions feeling a mysterious chill, as if "a psychotic snowman had crept up behind her and was breathing down her neck." Annabeth wishes she could pray to her mother, but this would be impossible, as Athena had appeared to her about a month earlier—an encounter Annabeth describes as horrible. Athena also had given Annabeth the worst present of her life during this meeting. Soon, the horns from Camp Jupiter blew from below as the campers had spotted the Argo II.

Annabeth Chase is amazed by the size of Camp Jupiter, which is twice the size of Camp Half-Blood, and notices the landmarks that Jason had told her about. She sees evidence of the Romans' recent battle, including the cracked dome of the Senate House.

An explosion nearly knocks Annabeth overboard, and Terminus, the Roman god of boundaries, appears on the Argo II. He shrieks that he will not allow any weapons inside the Pomerian Line, and grumbles at Jason for consorting with the enemies of Rome, referring to the Greek demigods. Piper tries to charmspeak Terminus, but he slaps her dagger out of her hand with magic for her impertinence. Since New Rome is still recovering from the recent battle, Terminus announces that if he was at his full strength, he would have already blasted the "flying monstrosity" out of the sky, to which Leo takes offense to. Annabeth tries to regain control of the situation and calm everyone down by introducing herself to Terminus, but the god finds Annabeth being the daughter of Athena, the Greek form of Minerva, to be "scandalous." However, before Annabeth can question Terminus on what he means, Jason interrupts and asks for permission to land inside the Pomerian Line.

Terminus instead tells them to "surrender, then leave," and slaps Leo's face for asking what the options are. This interests Leo even more and he asks if he can take a look at Terminus' gears, thinking he is an Automaton. Terminus makes Leo drop the screwdriver, announcing "weapons are not allowed on Roman soil inside the Pomerian Line," which includes the Argo II itself, as the whole ship is a weapon. Annabeth spots Percy walking with Frank and Hazel as if they were best friends, and Annabeth knows she had to reach him, as she was so close. She also notices that he is now a Praetor, as he is wearing a purple cape just like Jason's.

Annabeth orders Leo to stop the ship as she asks Terminus whether there is a rule against the ship hovering over New Rome, to which Terminus says there is not. Annabeth then tells Terminus that they will keep the Argo II up in the air over New Roman and use a rope ladder to reach the forum. She also promises Terminus that all the weapons will stay on the ship, as long as the legion reinforcements will honor the same rule, which Terminus agrees to as he cannot tolerate those who break the rules.

When questioned by Leo who asks if this was a good idea, Annabeth clenches her fists to stop them from shaking. She feels the cold presence, which seems to be laughing at her and the bad choices she is making. But she knows that Percy is down there, and that she has to reach him. She replies that it will be fine and Terminus will make sure that both sides will obey the rules, if Terminus agrees. Terminus sniffs, but agrees "for now," and allows them to climb down the ladder to New Rome, but pleads them to not destroy his city.

The five demigods climb down a ladder and walk through the crowds of Romans to Reyna, the praetor, and Percy. Reyna starts to speak, but Percy and Annabeth run into each other's arms, and kiss each other. She then suddenly suddenly slams Percy into the stone pavement, sending the Romans into a fury, and tells him to never leave her again. Jason then introduces the rest of the demigods. After the introductions, Reyna calls forth the Centurions to discuss something and tells the spirits in the kitchen to prepare a welcome feast. Octavian is flabbergasted that Reyna is letting the "intruders" into camp. Reyna dismisses him to go read his auguries and they go to the feast.

Reyna calls a toast for friendship, and soon after all parties start to exchange stories about what they had been going through for the past year. Eventually, Octavian recites the Prophecy of Seven, but Annabeth interrupts him and finishes the sentence. They realize that the Prophecy of Seven is meant for Greeks and Romans to combine forces to close the Doors of Death. Tyson then calls for his brother, Percy, to tell him that Ella is scared. Ella starts mumbling about about different ships that have sunk and notices Annabeth. Once she does she starts reciting a prophecy. Because no one except for Percy, Hazel, and Frank knows that she had once read the Sibylline books, they attempt to make it sound like she is spouting nonsense. After having convinced Octavian it was not a prophecy, Tyson and Ella shadow travel with Ms. O'Leary to somewhere safe.

After the ordeal, Octavian still does not trust the Greeks. In order to prove to Octavian that the Argo II is not dangerous, Leo takes Octavian on board the ship and shows him around. Jason then asks Reyna if it is alright for him to show Piper around, oblivious to the tension between Reyna and him. Percy, also wanting to show Annabeth New Rome, attempts to leave, but Reyna stops Percy and tells him that she wants to talk to Annabeth privately.

While Reyna is walking with Annabeth through New Rome, she calls for her dogs, Aurum and Argentum. The girls discuss the differences between Minerva and Athena. Reyna denotes there are no children of Minerva at Camp Jupiter, and that if they were to come there, they would be artists — not warriors or leaders on quests. Annabeth then realizes that she has met Reyna before at Circe's Island. They walk all the way to the Garden of Bacchus, which is Reyna's favorite place in Camp Jupiter, and appreciate the view. Reyna explains that she had wanted to talk to Annabeth to learn the truth. Instead of Annabeth feeling bad about her not being able to trust anyone at Camp, she talks about her family, growing up, and adventures in Camp Half-Blood.

Throughout the conversation, Reyna mentions that while she was on Circe's Island, she met a son of Athena, who washed up on the shore and rambled about the Mark of Athena. Then, a sudden, large explosion makes a crater in the forum of New Rome. The Argo II then proceeds to attack the city. Reyna and Annabeth rush down to the forum. Since Roman's are not allowed any weapons inside the Pomeranian Line, they start to throw food, rocks, and plates at the Greeks. Piper and Jason try to calm the angry mob by telling them they would never attack New Rome, but fail. Right outside the Pomerian Line the Roman's set up catapults to fire on the attacking Argo II.

Annabeth then sees Percy using water from a fountain to dose the angry mob of Romans. Octavian comes down the ladder screaming that Leo has fired on everyone. Percy asks if Hazel and Frank are coming with them on the ship, to which the two say yes. Hazel calls for Arion and distracts the crowd by riding straight through it. Frank, in attempt to let Percy and Annabeth climb the rope, changes form into a dragon. Once Percy and Annabeth are up, Leo is tackled to the ground by Percy and falls on his head. Annabeth then takes charge of the ship and leaves Camp Jupiter as quickly as possible.

On the Run
Once Leo finally wakes up, he is questioned by Annabeth about why he set aim at the Roman Camp. Leo responds by saying that he has no idea why he did it. Leo talks about how he had felt a cold presence and does not remember anything from then on. Frank comes from below deck to aboard the Argo II and tells Annabeth that she should really come downstairs. Before Annabeth leaves, she asks Frank to watch Leo. After a brief silence Frank asks Leo if he is sure that his name is not Sammy. Leo gives him a questioning look and tells him no. Leo tells Frank that he needs to do a damage report with Festus. The two proceed to go check on Festus.

As they walk up to Festus, the head does a 80 degree turn to look at them. Frank, startled, screams that "it's alive". Leo continues to receive the damage report from Festus and states that they need tar, lime, and Celestial Bronze. Festus notices that "AY-zuhl" is down below. Frank tells Leo that they need to land to pick up Hazel and Arion. Before they land, they do a scan to make sure they can find all the items in a nearby area.

While the scan is happening, Annabeth and Percy walk back up to report that Jason is doing well and that Piper is watching over him. While Leo is telling Annabeth about the damage report, Festus finds an area where all the items are. The area is Salt Lake, Utah. While descending everyone went downstairs to strap themselves in for an ugly landing, except for Coach Hedge who continues screaming, "Bring it on, Lake!"

Annabeth, Percy, and Frank leave to get tar, while Leo and Hazel leave to find Celestial Bronze. Piper stays on board and waits for an unconscious Jason to wake up, alongside Coach Hedge.

While searching for the bronze, Hazel and Leo encounter Nemesis, who gives Leo a fortune cookie, telling him to open it when he really needs her help, but says that the help will also have a high price.

Hazel and Leo continue on, and come across Echo, who is trying to save Narcissus as both of them had been brought back from the underworld. Narcissus is being obsessed over by nymphs, while he is staring at the reflection of himself through the lake, into a large sheet of Celestial Bronze.

Leo distracts Narcissus and the Nymphs with the help of Echo, while Hazel retrieves the Celestial Bronze. Leo and Hazel are pursued by the upset Narcissus and the Nymphs while they run back towards the Argo II.

Piper continues to take care of the unconscious Jason. Piper looks into her dagger, Katoptris, and sees many unsettling images such as a vision of a man in purple next to a Topeka 32 road sign and another man dressed in purple clothes. After Jason finally wakes up and the two groups return, the seven convene and then decide to head to Topeka to meet with Bacchus. Leo brings the ship in for a landing but unfortunately lands approximately eight miles from their destination. Jason and Percy each say that they have a friend who could give them a ride, resulting in them making a bet to see whose friend would get there first. Jason whistles for Tempest while Percy calls for Blackjack. Blackjack eventually flies out of the sky mere moments before Tempest. Percy rides on Blackjack to the right location while Piper and Jason ride on Tempest down below. When they get to the mile marker next to a wheat field, Percy comments that there is no sign of the "wine dude." At that moment, a very annoyed Bacchus exits the field and claims he is waiting for Ceres to talk about how Gaea was destroying the plants. Percy and Bacchus get off to a rough start, bantering back and forth with each other, causing Bacchus to become incredibly annoyed, even threatening to turn him into a dolphin. When Piper realizes that Percy is not helping matters, she interrupts the two and tells Bacchus she had a vision that he would help them. Bacchus starts to give them advice about how to throw a good party, but Piper explains that they need help on their quest. Bacchus remembers when he first fought the giants back when he was only a demigod, helping to defeat the twin giants Ephialtes and Otis. Piper takes this as a sign that he is part of their quest but Bacchus says that he is no longer a demigod and does not do quests anymore. When Piper tells him that he has to help them, the god gets angry and claims he would only help if they offered him tribute, something he claims they would never be able to do. However, he does tell the group to seek out Phorcys for information on Gaea, before realizing that Ceres would only be late if she felt there was a trap waiting for them, causing the god to flee the area.

Just after the god leaves, Gaea makes her move as two more Eidolons take control of Jason and Percy. Gaea tells Piper that she only needs a boy and a girl demigod, and that Piper would have to choose which of the boys will die. Piper is unable to make the choice and tries to stop the boys from killing each other, leading to Percy knocking Jason off Tempest. Piper then uses charmspeak to slow Percy down so he doesn't kill Jason, which gives Jason time to knock Percy off Blackjack with a bolt of lightning. Just as Jason goes to finish him off, Piper makes him stop, giving Percy the opportunity to knock Jason out by sweeping him off his feet. As Percy goes to kill Jason, Piper manages to gain his attention long enough for Blackjack to knock Percy out with a hoof to the head. Piper then has Blackjack carry them back to the Argo II where the two are treated for their injuries.

While they no longer seem possessed, Jason apologizes to Percy saying that he could have killed him, but Percy claims that he also could have killed Jason. Piper intervenes saying that the demigods ought to talk about what they learned from Bacchus and Annabeth called a meeting in the Mess hall. At the meeting, the discuss how the Eidolons had taken control of Percy and Jason as well as Leo, which makes it clear that the latter was not responsible for the attack on Camp Jupiter. However, despite knowing the truth, they have no evidence to support this and Octavian has gotten the Romans so frenzied that they would not listen anyway. Jason also informs them that the Romans would not follow them into the Mediterranean Sea as it is considered to be off limits, meaning that if they went there they would be considered traitors to Camp Jupiter. However, the Roman troops would not follow them to the sea. They also talk about the twin giants and how Gaea wants two demigods, leading Leo to remember what Khione had said at the Wolf House how Jason's blood would taint the area for generations. Percy also remembers how Polybotes wanted to capture Percy and use his blood to water the stones of Mount Olympus and wake Gaea. Percy suggests that until they figure out what Gaea wants, they ought to try their best not to be captured. They end the meeting by saying they need to find Phorcys, but Piper stops them as they get ready to leave. She tells them that the Eidolons are still present and that she has a plan for getting them off the ship. She uses her Charmspeak to call them out, leading Percy, Jason, and Leo to once again be controlled by the spirits. While the Eidolons fight back against Piper's charmspeak, they are eventually forced to swear on the River Styx never to take control of an Argo II crew member or return to the ship, causing the Eidolons to give up their borrowed bodies.

That night Percy has a dream about his time in Alaska, about how he had almost drowned in muskeg and what it really meant to suffocate. However, the dream eventually turns to Otis and Ephialtes, who reveal that they are preparing to destroy Rome on the first of July. As they leave, Percy sees a jar and pulls himself inside of it to be able to see what it contains. Once inside, he finds Nico di Angelo in a meditative state, using pomegranate seeds to keep him alive as the jar had very little air, leading Percy's fear of suffocation to scare him. Percy calls out to him, but Nico does not hear him and remains in his trance. As Percy calls out to Nico, saying that they will save him, he is waken up by Annabeth who tells him to brush his teeth and hair as she wants to show him something.

Annabeth takes Percy down to her favorite spot on the ship, the stables. Leo had designed the stables for pegasi, which are free spirits and prefer to fly free, meaning the stables are always empty. They wrap themselves in a blanket and look down through the clear bottom of the boat. Annabeth asks Percy if this place reminded him of anything, and Percy thinks back to the time they were in the Kindness International truck, but is unable to figure out why such a depressing time would lead to the stables being her favorite spot on the ship. She explains that the back of that truck was the first time they really connected, pulling out her camp necklace to see the ring from her dad. Percy then tells her about her dream and Annabeth asks him if Poseidon has talked to him at all, which Percy says has not happened. When he asks her if she had heard from Athena, she admits that they had had a fight and that she has been having nightmares, but the two agree not to talk about any more depressing things. The two eventually fall asleep, leading to the rest of the crew to think they were kidnapped at some point in the night until Frank finds them. As punishment for scaring everyone, Coach Hedge grounds the two, telling them that they were not allowed to be alone together anymore.

Once they arrive in Atlanta to search for Phorcys like Bacchus had suggested, Coach Hedge refuses to allow Annabeth and Percy to go search together, so Hedge, Frank, and Percy go down to the city instead. When they ask a lady named Esther if she knew where they could find salt water in a landlocked city, she suggests the aquarium and drops them off herself. Once in line, they notice they have very little mortal money and cannot afford to pay for entry. Just then, a lady with a name tag that says Kate appears and swoops up the three denarii Frank was holding and offers them the VIP tour. Hedge notices that Kate is not a human and they begin to expect a trap, but follow her in hopes of finding Phorcys. She shows during the tour that she has expert knowledge on larger sea animals, but cares little about smaller fish. Once they reach the sea monster exhibit, it is shown that several of the monsters are tranquilized. Kate also drops a few hints that she knows about the three already, as she knows Percy is a son of Poseidon and Hedge is a satyr. Phorcys appears soon after and Kate points out that their name tags are wrong, revealing herself to be Keto, the mother of sea monsters. Phorcys becomes annoyed with her more informational stance on the tour as he feels it will bore customers, but she and Hedge walk off to talk some more, leaving Frank and Percy with Phorcys.

Frank and Percy flatter Phorcys' use of fireworks and a disco ball, getting him to talk about Ephialtes and Otis, twin Gigantes that together make up the anti-Dionysus. He also explains that they have a prisoner trapped in a bronze jar to use as bait for the crew of the Argo II. When asked about Gaea's plans, he explains that her plans have many layers and that she placed a bounty on a few demigods. He also mentions that even if they found the map in Charleston leading to Athena Parthenos in Rome, they would be doomed before they ever reached the city. After that, he continues the tour and leads them to another exhibit, but it turns out to be a trap and the two are trapped in a large tank, as Phorcys plans on having daily shows where the two fight sea monsters. He leaves them trapped, but Hedge and Keto pass by the tank a moment later. Percy manages to get Hedge's attention, and he acts calmly before kicking Keto in the back of the head. The three then attack the same spot of the tank and free themselves before escaping back to the Argo II and they fly off to Charleston.

On their way, they begin to talk where the map might be, and Jason suggests Fort Sumter or a place called the Battery, a place he and Reyna had been to before. When they get there, they see a ghost and Reyna talking to it alone. However, Reyna refuses to tell Jason what the ghost had said. They also learn that the Roman eagles are right on their tail. To try and lead them away, Leo sends Buford on a decoy trail with a bag of dirty laundry to lead the Roman eagles away and maybe delay them.

That night, Annabeth remembers the meeting she had had with her mother a few months ago. After leaving Sally's apartment, she had gone to take a train at the Grand Central Station and seen her mother looking at a map. She had seemed confused and did not even recognize Annabeth. Annabeth had questioned if the goddess was actually Minerva, her Roman form, but she had yelled at her to never call her by that name again. She had claimed that she had been Athena before the Romans had destroyed Athens, taken away her title as a war goddess, and stolen her statue. In order to avenge her, she had ordered Annabeth to follow the Mark of Athena and handed her a small subway token that changes into a small silver coin. When Annabeth had noted that she needed help in finding Percy, the goddess had claimed that she did not care for him and if he had joined the Romans, he should perish with the rest of them. She had also added that if Annabeth would help the Romans, she would be no child of hers.

Back in her cabin, Annabeth hears a knock on the door and Frank walks in, asking for advice. He shows her a pair of Chinese finger cuffs that he could not figure out the trick to earlier. (Something some of the others laughed about.) Annabeth uses her laptop to scan the toy and shows Frank how it works. She explains that when he pulls tight, the fabric will tighten as well, preventing the fingers from escaping. The only way to get out is to push your fingers together and take it off that way. While Frank is grateful, he wonders if Annabeth really had to bring it up on the computer and could have just shown him. Annabeth admits she could have just done that as well, taking some advice from Frank to just keep it simple. He is also about to ask her if she could help him find an answer to prevent his stick from burning up, but is cut short when the dinner bell rings.

Once docked in the harbor at Charleston, Annabeth, Hazel, and Piper McLean agree to search for the ghost of the Battery while Frank, Leo, and Jason agree to search the museum for any sign of the map. Percy, on the other hand, goes to the harbor to see if there is a way to free the monsters and creatures back in Atlanta. When they see the ghost, Hazel points out that there is no way it was a spirit as no spirit glows that brightly. They approach the spirit who is actually Aphrodite, Piper's mother. She sits them down for tea and begins to give Annabeth and Hazel some beauty tips, before Piper stops her after feeling embarrassed of her mother's actions. When Annabeth asks if she is Aphrodite or Venus, she explains that she never really changed when the flame of Western Civilization moved to Rome, because love is universal so she is both. That is the reason why she is not affected by the Civil War as much as the other gods. Hazel protests, saying they are not at war yet, but Aphrodite only compliments her optimism and says that war is coming, along with many heartbreaking days. After remembering all the parties in the old days of the south, Piper gets her back on track and Aphrodite says she is here to help as Hera has been kicked off of Olympus by the other gods. When she mentions the fight between Athena and Annabeth, she explains that Athena was the most Greek of all gods and the Romans insulted her by limiting her to crafts and cleverness. From this, Annabeth figures out that what they are searching for is Athena Parthenos, the statue of Athena that went missing thousands of years ago. The Greeks never forgave the Romans for this insult, while Athena and her children made it so the two groups ended up fighting. Just then several war eagles appear and Aphrodite tells them that the map is at Fort Sumter, the location of the first battle of the Civil War.

As they race for the ship, Octavian cuts them off with two bigger guys to back him up. When they try to explain that Leo was controlled by the Eidolons, Octavian says they cannot hear them because they have wax in their ears (so they cannot be controlled by Piper's Charmspeak). Annabeth tosses her knife into the water when Octavian tells them to lower their weapons. Just as Octavian tells the other two to lower theirs, the water around the rock erupts and traps the Roman soldiers in a small whirlpool that Percy creates. Percy then hands Annabeth her dagger with a poker face and says, "You dropped this." They climb onto the Argo II and sail toward the fort, sending an Iris Message to Jason and his group to warn them. When Jason, Frank, and Leo are trying to make it back to the ship, Hedge fires a shot at the Romans which causes the group to fall behind the walls of the fort. Annabeth orders the demigods on board to defend the ship while she rushes into the fort to find her friends. Once inside, she orders them to the ship while she goes to find the map. She enters a room looking for the map and the walls begin to fill with spiders. As Annabeth cannot move from her fear, Gaea tells her that she will meet the weaver soon and how she would have preferred Annabeth as a sacrifice. Gaea's voice fades and is replaced by a flaming owl that burns away the spiders and leads Annabeth to the map.

Once she has the map, Annabeth is confronted by Reyna with her two dogs, Argentum and Aurum. When Annabeth starts to explain how Gaea is trying to separate the camps, Reyna tells her to save it for her trial. When Annabeth claims that the Giants have won if they fight, Reyna says she has no choice as she can no longer control Octavian. If Annabeth agrees to return for a trial, she will be executed, but some kind of peace can be achieved. While Annabeth refuses, Reyna points out that this is the better option and that if Octavian does not get blood, his attention will turn to Camp Half-Blood instead. This saddens Annabeth, but she claims that she can fix the rift between the two camps and thus persuades Reyna into letting her go. However, the latter says that the next time they meet, they will be enemies. Annabeth only asks that Reyna slow Octavian down before reaching the camp. After their meeting, Annabeth runs back to the ship while Jason and Percy call forth a storm to push the Romans back. Once Annabeth is on board, they sail off to the Mediterranean Sea and Rome in order to save Nico and find Athena Parthenos.

Entering the Mediterranean Sea
They reach the Mediterranean Sea and see the Pillars of Hercules, which are guarded by Hercules. The heroes then decide to send their best speakers, Jason and Piper, to talk to the god. They talk to him for a while and the god says that he will give them an easy quest since one has to complete a quest to get permission to enter the Mare Nostrum. Jason mentions Hera, however, and because Hercules hates the goddess, he changes his mind and gives them a harder quest. Their quest is to get the horn of Achelous to humiliate the god even more, as Hercules had already taken his other horn.

The two demigods get the horn and go meet with Hercules again. The god gives them permission to pass as they had retrieved the horn. He then asks to have the horn, but Piper refuses to give it to him claiming he does not deserve something as precious as the cornucopia. This angers Hercules and he prepares to kill them all, but Piper releases an unprecedented amount food from the cornucopia, which completely buries the god. Jason then flies them to the ship and they start to take off. Hercules manages to escape from under the food, but is quickly knocked back down as Percy hits him with a ten-foot tall wave of water. As they fly off, Hercules starts to chuck the food at the ship, managing to lodge a few coconuts in the hull of the ship, but the demigods manage to escape nonetheless.

After sailing into the Mediterranean Sea, the ship is frequently attacked by Stymphalian birds, Venti, and a wild pegasus that steps on Gleeson's enchiladas. Percy goes to sleep while Jason keeps watch and has a dream about Otis and Ephialtes talking with a figure he cannot see. They report that the group should be at Rome a little after daybreak if they manage to get past the golden boy. Ephialtes reminds the figure that Gaea wanted Annabeth alive for the sacrifice, but the figure says that the others could be used instead. Ephialtes simply says that Annabeth and Percy are preferred, but the figure shoos them away and the dream dissolves. Jason knocks on the door and tells Percy that it is his tern to take watch, as they are now in water. Percy wakes up Annabeth and tells her about his dream. Annabeth makes Percy promise not to tell the others about his dream because it would only scare them. Percy has a strange feeling and orders the ship to stop. It is too late, however, as another ship comes out of the fog and rams into the Argo II. Grappling lines attach to the rails and in an instant, the entire ship is overrun by dolphin warriors. Their captain soon arrives on deck and instantly disarms Percy, sending Riptide splashing into the sea.

The man introduces himself as Chrysaor, also known as the "golden boy" because of the golden Gorgon mask he wears in honor of his mother. Chrysaor's crew tie up everyone on board except for Frank, who had managed to hide, and start to ransack the ship, stealing anything worth value, including a box full of Greek Fire. Chrysaor begins to make plans, including selling Hazel Levesque and Piper McLean to Circe, while keeping Annabeth and Percy for a sacrifice to Gaea. Hazel and Piper begin to thrash around just as Riptide returns to Percy's pocket. Percy uses the distraction to try and surprise Chrysaor, but he is quickly defeated again. Having to think quickly, Percy begins to tell Chrysaor and his dolphin men that because the crew of the Argo II failed to finish their quest, their "captain" would get very upset. Chrysaor claims that there is no one else on their ship, but Percy says that gods only appear when they want, and claims that their captain is Dionysus. The dolphin men become nervous as Dionysus is the god that had originally turned them into dolphins. Chrysaor tries to keep order but Percy goes on, saying that the god had driven Piper and Hazel mad a few moments ago when they thrashed around. Percy notes that the cooler on the ship has a can of Diet Coke, which is Mr. D's favorite soda, and that Dionysus would soon turn them all into dolphins as punishment. Frank then appears from his hiding spot and transforms into a dolphin. This scares the dolphin warriors off the ship and Chrysaor is backed into a corner by the crew. His mask is knocked off and he jumps over the side, escaping. Percy then sinks Chrysaor's ship by filling it with Diet Coke and offering it to Dionysus as a tribute.

Arriving in Rome
The crew decide to go by air, and Percy heads back to bed but has a dream about Gaea. She shows him a vision of Camp Half-Blood turning to ash and dirt. She offers to spare this place if he brings Annabeth and himself to her willingly, but Percy wakes up and finds that they have arrived in Rome. They land in a park and start to make plans. Annabeth plans on going to the Tiber River alone, but Percy convinces her to allow him to go with her for protection, while Hazel, Leo, and Frank try and find Nico di Angelo by having Hazel try and sense him. Gleeson Hedge, Jason, and Piper would stay behind and watch the ship.

Percy and Annabeth walk around Rome, visiting some of the sites, but ultimately going to the spot marked on Annabeth's map. They eventually arrive at the spot, but they are unsure of what to do an end up having lunch. Soon, a Vespa pulls up to the table and two people that look like old movie stars appear, introducing themselves as Tiberinus and Rhea Silvia (mother of Romulus and Remus). They offer to bring Annabeth to the start of her quest, but refuse to take Percy when he asks to go just a bit farther with her. Rhea Silva tells him that he has a different path and that Piper's knife will lead the way to the giants. Percy reluctantly allows them to take Annabeth and heads back for the ship. Tiberinus and Rhea Silva drive Annabeth around Rome, telling her so many details about the history of the city that it makes her head spin. They also talk about the children of Athena that came before her and how none of them ever made it to the prize, but if Annabeth can do it, the tide of the war could change. They then drop Annabeth off to an entrance leading to the Roman underground and the start of Annabeth's quest.

As Annabeth gets deeper under the city, she reaches her first hard challenge. She reaches a long drop down, but has no way of getting down and laments that fact that she does not have any kind of special powers like the other seven do and her only magical item no longer works and is back in her cabin. A voice tells her that she has intelligence, giving Annabeth the drive to move forward and makes a rope ladder using plastic swords and kite string. She climbs down, but keeps the string just in case she needs it later. She continues on and enters a shrine to the god Mithras, littered with the skeletons of past children of Athena. Several ghostly worshipers of Mithras appear and ask Annabeth a series of questions about the god. Despite Annabeth not knowing anything about Mithras, there are clues all over the room and Annabeth manages to fool them into believing she knows everything about their god. As a show of power, she then hits a capstone holding the room together and the shrine begins to crumble. Annabeth escapes the room, but falls down a small pit and ends up breaking her ankle. She uses some Ambrosia to lessen the pain, then finds some boxes left in the room by the Hermes Express, but they only contain bubble wrap. However, she uses the bubble wrap and some string to make a cast to hold her ankle in place while it heals. For her last test, she walks into a hallway filled with spiderwebs and weaves a pathway across a large ditch as the spiders start to follow her, but do not follow her across. Annabeth then enters a large room lined with beautiful tapestries but is quickly captured by their weaver, Arachne.

Meanwhile, Leo, Hazel, and Frank end up getting lost in the city as Hazel has a hard time getting a lock on anything with so much under Rome. They eventually find their way to the Pantheon and Leo quickly spots a secret lock leading to a small entryway downward. Hazel agrees to take a look, leaving Leo and Frank along together. The two open up a bit, with Leo even pointing out they both lost their mothers to fire in some way. Leo even offers to find a way to help Frank find a solution to keep his stick safe, but they are interrupted when the Eidolons appear, forcing Leo and Frank down the hole, where they meet back up with Hazel. They find a sphere that acts like a lock, with Leo finding the right combination and entering a room full of failed duplicates of Archimedes' inventions, including a few automatons. While exploring the workshop, the Eidolons take control of the automatons and an electric sphere, quickly knocking out Hazel and Frank, but Leo escapes into a control room and locks it behind him. Leo finds a control sphere for everything in the shop, but is unable to find the right password before the Eidolons turn their attention to Frank and Hazel. Leo uses the fortune cookie Nemesis gave him to ask for the password, allowing him to take control of the machines and trapping the Eidolons inside forever. When Hazel questions why her senses lead her to this workshop, they find Nico's Sword and realize it was a trap. Gaea appears in a mirror and taunts them, as the three are now separated from the others and inside the earth, but Leo burns the mirror as she was annoying him.

Back at the Argo II Piper sets up a picnic for her and Jason using the Cornucopia, but a birthday cake comes out with the rest of the food and Jason admits it is his birthday. Percy soon returns and tells them about Annabeth and asks Piper to look in Katoptris for a way to the giants. She does, but it shows her a vision of Camp Jupiter setting up a forward base and setting up an invasion route into Camp Half-Blood. The vision changes and shows a spiral staircase near the forum, a place the knife had shown them all dying earlier to Piper. Percy and Jason convince her to go and they find the staircase. Percy goes down first in case there is water, as he can breath in water and will not drown. When he comes back, he tells them he had found something weird, which turns out to be a Nymphaeum. Soon, the nymph Hagno and several others — the nine nymphs that watched over Zeus when he was born — appear and flood the chamber with evil water. Percy is unable to breath and the nymphs begin to drain the three of their power, stealing Percy's control over water, Jason's control over the rain, and Piper's beauty in order to be young again. Piper comes up with the idea to funnel all their positive thoughts into the Cornucopia, which releases the positive emotions as clean water. As the three release almost all their power into the Cornucopia, the nymphs become young again and spare the three, as the power they gave them as a gift and they restore the trio back to full strength, as well as telling them the location of Otis and Ephialtes.

The three quickly arrive at their lair and find the jar Nico di Angelo is in unguarded. When they approach it, a platform lowers with one of the twin giants on it, Ephialtes. Otis soon joins his brother and they begin to talk about their plan to release monsters into Rome to destroy it as their biggest show yet. They had also planned on letting Nico die in public, but because of his "death trance", he has been asleep and has no entertainment value, leading to the giants tipping over the jar and releasing him. Nico rolls out and Percy is unable tell if he is alive or not. Percy tries to keep the giants distracted as Nico wakes up and begins to crawl away. The twins mention that even if Percy should be kept alive for the bounty, Annabeth is already doomed and Leo, Hazel, and Frank are locked up, meaning the giants can kill Percy, Jason, and Piper. (The twins even claim to have choreographed their deaths.) They also mention that Gaea will rise in only a month. The three prepare to fight, with Jason attacking Otis, Percy attacking Ephialtes, and Piper trying to defend Nico from the released animals and monsters. A hydra is released, leading Percy to set a large stack of fireworks off, which destroy the hydra, but also destroy many different areas of the twins' hypogeum and knocking out Piper. When Jason runs to her, Otis tosses his spear at him, which Jason deflects with a gust of wind and it strikes Ephialtes right in his side, turning him to dust. A piece of the ceiling then falls on Otis, turning him to dust as well. However, the two need to be killed by a god and demigod working together and they instantly reform. As they taunt Percy and Jason, Bacchus appears on the scene and raises them into the Colosseum, which Bacchus fills with ghostly spectators. However, Bacchus refuses to help unless the two can "entertain" him.

Jason and Percy agree to fight together this time and charge the two. Jason blasts the giants with wind, causing the fake mountain the two were holding to fall on Ephialtes. After insulting Swan Lake, Otis charges the two and Jason blows him into the lake and the two stab him with their swords, turning him to dust. Percy then uses the water to keep the dust from reforming, but Otis' head is able to reform. Ephialtes then escapes from the fake mountain and charges the two, managing to disarm them both and almost kills them, but the Argo II appears overhead and blasts the giant with Greek Fire from the cannons. Bacchus considers this entertaining enough and stabs both giants with his thyrsus, defeating them. Before leaving, Bacchus informs them of the best place to reach Annabeth before she is killed and vanishes. Leo, Hazel, and Frank rejoin Percy, explaining that Frank turned into a weasel and dug to the surface, where they managed to call Coach Hedge to rescue them.

Back on the ship, Percy becomes angry at Nico for not telling him about his past when they met at Camp Jupiter and the fact that Nico knew about both camps the entire time. Nico explains that Hades had shown him the camp as he knew that both camps would have to work together. Nico also goes on to say that he knows where the Doors of Death are located in: One in a temple in Greece called the House Of Hades and one in Tartarus. Also, both sides have to be closed or the doors cannot be closed at all. However, there is an army of Gaea's forced guarding the doors and the monsters are even stronger in Tartarus. The demigods agree to worry about this later and head off to save Annabeth.

Reuniting
Annabeth is still trapped by Arachne. Despite being terrified, her brain begins to work and she thinks of a plan, as she uses Arachne's hubris against her. Annabeth tells Arachne that she is the new architect of Olympus and that she can display her tapestries on Mount Olympus, which would be a great insult to Athena. Annabeth also tells Arachne that she may even become a god and could use her tapestries to mock Athena for all time. Arachne is slowly sucked into Annabeth's words and agrees to make something to be displayed right in the Hall of the Gods. She shows Arachne a picture of Frank's Chinese finger-cuffs on her laptop, but it is so large that Arachne would need a lot more silk. Annabeth suggests using some thread covering the Athena Parthenos, which Arachne agrees to. When she finishes, Annabeth points out a flaw in the middle. Arachne, unbelieving, goes inside to check, but finds herself stuck when she tries to puller herself free. Annabeth's own hubris shows itself when she teases Arachne that she has done Athena a great service by keeping the statue safe and it alone should be displayed on Olympus. Arachne thrashes around, almost destroying the floor below them, leading directly to Tartarus, but the Argo II arrives and blasts a hole in the ceiling.

Everyone works together, quickly loading Athena Parthenos into the ship as the floor collapses, leading to Arachne falling through the floor. Annabeth starts to walk to a ladder, but a thread attaches itself to Annabeth's leg and pulls her into the pit. Percy manages to grab her arm and holds her, preventing them from falling but still unable to pull himself up. Nico calls for help while Annabeth tells Percy to let her go. However, Percy makes Nico promise to take the others to the Doors of Death on the mortal side, which he does. He then turns to Annabeth and tells her that they will be together and he will not let her go. She agrees and tells him as long as they are together, before Percy lets go of the ledge he is holding and they fall into Tartarus.

Ending
Back on the ship, the crew feel like they could have done something to prevent Percy and Annabeth from falling into Tartarus. Nico tries to comfort them, saying that even if Jason had flown down or Frank had turned into some animal, the two were so far down that they would have been pulled in as well. He also says that Percy is the most powerful demigod he knows (including the other seven of the prophecy) and he will do everything in his power to keep Annabeth safe. Everyone is still down, however, until Leo encourages everyone. He declares that he will use the sphere of Archimedes and ancient scrolls to upgrade the ship with new weapons so that Gaea will not know what hit her. He also says he will save Annabeth and Percy, even if he has to make a crane that will reach all the way to Tartarus. Festus agrees with him and they set sail for Greece, with Leo saying "Festus, raise the sails. We've got some friends to save."

Chapter List
There are no chapter titles. Each chapter has a name of one of the main characters and is written in Roman Numerals. There are fifty-two chapters going alternately in the order of Annabeth, Leo, Piper, and Percy. Each character gets four chapters before it shifts to another character.

Prophecy
A prophecy by Ella the Harpy, while with Percy, Hazel, and Frank, refers to this as well. Translated from Latin to English, it says:

''Wisdom's daughter walks alone, The Mark of Athena burns through Rome. Twins snuff out the angel's breath, Who holds the key to endless death. Giants bane stands gold and pale, Won through pain from a woven jail.''

Unraveling of the Prophecy

 * Annabeth, daughter of the wisdom goddess Athena, walks alone through the underground of Rome or, as she puts it, she doesn't have any special ability like the other six heroes do, which is why she walks alone.
 * The symbol of the Mark of Athena glows bright red like fire making seem like it burns through several places in Rome.
 * The twin giants Ephialtes and Otis take away Nico di Angelo's air by putting him in a jar. Angelo is Italian for "angel."
 * Nico holds the information to the Doors of Death.
 * Athena Parthenos is made of gold and ivory, which are like pale stones.
 * The statue was rescued by Annabeth Chase from Arachne. Despite Annabeth's broken ankle that caused her extreme pain, she managed to win the statue by getting Arachne to weave her own jail.

Trivia

 * The Mark of Athena is the only book in The Heroes of Olympus series so far, where the character who narrated the first chapter does not narrate the last chapter.
 * The Mark of Athena shares some similarities to The Sea of Monsters:
 * A crew sail into the Sea of Monsters, the Bermuda Triangle in The Sea of Monsters and the original Sea of Monsters in the Mediterranean Sea in The Mark of Athena.
 * While Blackjack first appeared in The Sea of Monsters, he made his first actual appearance in The Heroes of Olympus series during The Mark of Athena.
 * Both books feature a pirate in them (Edward Teach and Chrysaor).
 * The main villain in each book is a creature that Annabeth is scared of. In The Sea of Monsters, Annabeth was scared of the cyclops Polyphemus because of a bad experience with a cyclops as a child and in The Mark of Athena, Arachne is a large spider, something all children of Athena fear.
 * In both cases, Annabeth managed to overcome her fear.
 * At one point when talking about the Doors of Death, it is described as being a hole in a dam. Percy makes a dam joke, which no one understands and he says it is an inside joke, referring to his trip to the Hoover Dam in The Titan's Curse.
 * The four narrators of the book are all children of the Greek forms of the gods.
 * Percy is about the same age in this book as Luke Castellan was when he first turned away from the gods. After Bacchus appears and only offers to help Jason and Percy fight Otis and Ephialtes if they can entertain him, Percy states that he understands better why Luke hated the gods.