The Heroes of Olympus Series Novels

The Blood of Olympus (The Heroes of Olympus 5) by Rick Riordan
The House of Hades (The Heroes of Olympus 4) by Rick Riordan
The Mark of Athena (The Heroes of Olympus 3) by Rick Riordan
The Son of Neptune (The Heroes of Olympus 2) by Rick Riordan
The Lost Hero (The Heroes of Olympus 1) by Rick Riordan