Rick Riordan The Trials of Apollo 2 Books Set Deluxe Cover, The Hidden Oracle, The Dark Prophecy

The Hidden Oracle (The Trials of Apollo Book 1)
Cast down from Olympus, he's weak, disorientated and stuck in New York City as a teenage boy.It's the first time he's been without his powers, and he has to survive in the modern world.

The Dark Prophecy (The Trials of Apollo Book 2)
There's only one way he can earn back Zeus' favour, and that's to seek and restore the ancient oracles - but that's easier said than done.