Percy stranded and lost, amnesiac and fleeing the gorgons, finds Camp Jupiter, the Roman camp of the demigods. He becomes friends with Frank and Hazel. Together, they win Capture the Flag for the fifth cohort. Mars then claims Frank as his son and launches a quest to save Thanatos, the Greek god of death, from LAceonus, a giant born to oppose Pluto, and gives Frank as quest leader. The trio must face many challenges such as the basaliks, the Amazons. (a tribe of women), karopis, griffins and very poor supplies. They also learn a lot about each other. Percy and Frank learn that Hazel was dead and came back to life, that Frank's life depends on a burning stick, and that Percy is Greek. Percy regains his memory after drinking gorgon blood to destroy Phineas. They also acquire the fastest horse in the world to escape the Amazons, Arion. With Arion's help, they reach the Hubbard Glacier, where they fall into a trap. A hundred shades of once-living demigods surround them, beyond Thanatos' control. Alceonus appears and taunts them. Thanatos tells them that only the burning stick on which Frank's life depends can...