The Trials of Apollo by Rick Riordan (series)

The Trials of Apollo is a young adult fantasy series by Rick Riordan.

Book #	Title/Author
1	The Hidden Oracle by Rick Riordan
2	The Dark Prophecy by Rick Riordan
2.5	Camp Half-Blood Confidential by Rick Riordan & Jesse Bernstein
3	The Burning Maze by Rick Riordan
4	The Tyrant's Tomb by Rick Riordan
4.5	Camp Jupiter Classified: A Probatio's Journal by Rick Riordan
5	The Tower of Nero by Rick Riordan