The Son of Neptune

The Son of Neptune is the second book in the Heroes of Olympus series written by Rick Riordan. It is set to be released on October 4th, 2011. Taking place around two months after the start of The Lost Hero, the Son of Neptune is told using alternate third person points-of-view of Percy Jackson and yet-to-be-named main characters.

Development
In an interview by Scholastic with Rick Riordan for The Last Hero, Riordan is questioned about the whereabouts of Percy Jackson. The author hints that the answer would be revealed as Jason's quest progressed. By the end of the book, he says that readers would have a good idea where the second book is going. It has led to speculation that the book would explore the events surrounding Percy and his involvement with the Roman Camp Half-Blood. On May 26, 2011, Riordan released both the cover art and the first chapter of the book confirming such speculation and can be read here.

The cover has Percy on drift ice with a glacier in the background. Percy is holding a Roman eagle on a poll. Riordan told of how he had to describe to John Rocco, the artist, of what the book was about, because the cover had to done before Rick had finished writing it. After he had finished his description to Rocco, he stayed up all night and he created the cover.

According to Rick Riordan's blog, revisions of the third draft were completed on April 2, 2011. Riordan then tweets on May 15, 2011, the manuscript is completely finished, revised and edited. All that was left was publishing, formatting, etc.

Synopsis
In The Lost Hero, three demigods named Jason, Piper, and Leo made their first visit to Camp Half-Blood, where they inherited a blood-chilling quest:

Seven half-bloods shall answer the call

To storm or fire the world must fall.

An oath to keep with a final breath, 

And foes bear arms to the Doors of Death.

Who are the other four mentioned in the prophecy? The answer may lie in another camp miles away, where a new camper has shown up and appears to be the son of Neptune, god of the sea. His name is Percy Jackson, a 16 year old teenager, who does not remember who he is apart from his name, being a demigod and Annabeth. As revealed in The Lost Hero, Percy's arrival is explained by Hera's decision to swap the leaders of both camps to unite the two camps in hopes of quelling the forces of Gaea and the Giants.