The Heroes of Olympus

The Heroes of Olympus is Rick Riordan's second Camp Half-Blood series after Percy Jackson and the Olympians, and focuses on Greek-Roman mythology instead of only Greek mythology like its predecessor series.

The Prophecy of Seven
"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."

The Seven Heroes of Olympus

 * Jason Grace: Roman demigod and son of Jupiter
 * Percy Jackson : Greek demigod and son of Poseidon
 * Hazel Levesque: Roman demigod and daughter of Pluto
 * Piper McLean: Greek demigod and daughter of Aphrodite
 * Frank Zhang: Roman demigod and son of Mars
 * Leo Valdez: Greek demigod and son of Hephaestus
 * Unknown

Main Series

 * The Lost Hero – October 12, 2010
 * The Son of Neptune – October 4, 2011
 * The Mark of Athena – Fall 2012
 * Book 4 – Fall 2013
 * Book 5 – Fall 2014

Companion Books

 * The Demigod Diaries - August 14, 2012

Audiobooks

 * The Lost Hero was made available as an audiobook read by Joshua Swanson on October 12, 2010, with a play length of 16 hours and 34 minutes.
 * The Son of Neptune was made available as an audiobook, read by Joshua Swanson, on October 11, 2011; a week after the release of the book.