The Trials of Apollo 4 : The Tyrant's Tomb

Though Apollo and some of his friends have emerged from the Burning Maze, rescued the Oracle and lived to fight another day, they can't escape the tragedy that has befallen them, or the terrible trials still to face.

So, with heavy heart, Apollo (OK, Lester) and Meg have a triumvirate still to defeat, oracles to rescue, and prophecies to decipher, so that the world may be saved, and Lester may ascend into the heavens to become Apollo once again.

But, right now, Caligula is sailing to San Francisco to deal with Camp Jupiter personally, and they have to get there first. Failure would mean its destruction.