The Battle of the Labyrinth by Rick Riordan

It's Percy Jackson's first day of school when he gets attacked by 2 empusai (vampire-like creatures) He destroys the first, but the second escapes. That is how the big adventure of "The Battle of the Labirynth" begins where Percy fights giants to laestrygonians to help the gods win the war between them and the Titans. The prophecy says that when he becomes of age one of the sons of the big three gods (Zeus, Poseidon, Hades) will hold the power to kill gods which will be the fall of Olympia or destroy the Titans.

Hisham, age 13, Ancaster Branch