Percy has escaped Echidna and Chimera by jumping off the Gateway Arch. When he lands in water, his wounds are healed. He also has a vision in which a woman tells him to go to Santa Monica. However, in the aftermath, it is clear even to mortals that something has happened. One reporter is suggesting that a young man matching the description of Percy Jackson—who ran away from home, ruined his step-father’s car and destroyed a bus—may be involved. Percy has become a fugitive.

Annabeth suggests that they attempt to contact Chiron by creating a rainbow with a water gun and then asking the goddess Iris to relay their message. However, they instead contact Luke. Things are not going well at Camp Half-Blood. In fact, it looks like it is going to be the Trojan War all over again. Athena has sided with Zeus, and Apollo, Artemis, and Ares have sided with Poseidon. When Percy shares his doubts that Hades is responsible for the theft, Luke agrees that Hades had to be the thief because he could have used his helm of darkness, which grants him invisibility, to steal the master bolt. Annabeth, who can turn invisible with her Yankees cap, could have stolen the bolt, but Luke says she would not do such a thing.

Percy, Annabeth, and Grover are out of money, but they still need to eat. They enter a diner but have no money. They are about to be turned away when a stranger offers to buy their meal. It is Ares, the god of war; he has shotguns on his motorcycle and fiery eyes that look like tiny nuclear explosions. Ares asks Percy to do a small job for him: to retrieve his shield from a nearby park. Although Percy dislikes Ares immediately, he agrees to help because the god offers to provide the young heroes with food and transport—and tell Percy about his mother.

Ares and his girlfriend Aphrodite, the goddess of love, were together in the Tunnel of Love ride. However, Aphrodite is married to Hephaestus, the blacksmith of the gods, and Annabeth explains that he once trapped Ares and Aphrodite in a net so the gods could laugh at them. Percy and Annabeth see the shield and proceed to pick it up, setting off another trap. There are mechanical spiders, thin threads of metal that make a net, and cameras with a live feed to Olympus. However, Percy and Annabeth escape and they return to shield to Ares. Ares gives them a backpack filled with food and gold, points out a truck that is transporting animals to Las Vegas, and explains that Percy’s mother is not dead. However, it is clear that Percy has made an enemy of Ares. Ares’s transportation is less than ideal. Although the truck claims to provide “humane” treatment for the animals within, the zebra, lion, and antelope are being abused. Grover learns that they are actually being smuggled. Percy and his friends free the animals when they get to Las Vegas.

Percy expects to be attacked by monsters, so he is on his guard. However, when they stop at a hotel, it seems like they have finally found a few moments of peace. The manager offers them LotusCash, which allows them to use the hotel’s facilities as much as they like. The young heroes bathe and rest before going to the games room. Once there, Percy meets a boy who claims to have been playing games since 1977. Percy realizes that this is another trap and manages to convince Grover and Annabeth to leave. When they leave, they discover that days have passed. They only have one more day to complete their quest and prevent war.