Replaced

It isn't too long after giant war when all of the sudden an unexpected guest shows up in the Poseidon cabin. The most strange thing about this "guest?" He's identical to the one and only Percy Jackson.

Percy doesn't know what quite is going on. All he knows is that he's trapped in a magical prison, and his evil twin wants to take over the world. Pretty difficult situation, huh? Percy must escape and save his friends... before it's too late.