Third Book of Destinies Series. A fall into the endless abyss. A journey never taken by the heroes of old. Percy Jackson and Zoë Nightshade embark on a quest to do the impossible. A race against time through the worst place in the mythical world. Can they reach the heart of Tartarus and close the Doors of Death or will Gaea win out and turn the mortal world to ash?

Jason, Thalia, and Percy Grace are all children of Julia Grace, lover of Zeus/Jupiter. The twins, Jason and Percy, have to be separated from Thalia due to their Roman heritage. When the boys arrive at Camp Jupiter, they don't know that in a couple years' time, they will both be thrust into two wars.