The Tyrant's Tomb (The Trials of Apollo, Book Four)

It's not easy being Apollo, especially after he's been turned into a human and banished from Olympus. On his path to restoring five ancient oracles and reclaiming his godly powers, Apollo (aka Lester Papadopoulos) heads to Camp Jupiter in the San Francisco Bay Area, where the Roman demigods are preparing for a desperate last stand against the evil Triumvirate of Roman emperors.