The story takes place after a modified version of "The Mark of Athena" young Percy Jackson has fallen into the depths of Tartarus by himself to allow his friends a chance to escape their. . . predicament. Read to find out what happens to these young demi-gods, Poseidon, and Percy's mother. Here's a question to ponder. Percy will come back, but how? hmm! Percy x Reyna just a tad.