In Denver, Annabeth leads Percy and Grover to an empty car wash so they can Iris-message Camp Half-Blood. They reach Luke instead of Chiron and learn that the camp is becoming divided because word of the conflict between Zeus and Poseidon has spread. Luke says many campers are taking sides, repeats his suspicion that Hades stole the master bolt by using the Helm of Darkness, and asks whether Percy is using the flying shoes. Percy lies that the shoes have been useful, and the conversation ends abruptly, leaving Percy uneasy.

Hungry and nearly out of money, the trio goes to a diner, where Ares suddenly appears and pays for their food. Percy recognizes that Ares can stir up anger and resentment, and Ares uses that pressure while offering a bargain: if Percy retrieves Ares's shield from an abandoned water park, Ares will arrange transportation west and may tell Percy something about Sally. Percy wants to refuse, but Annabeth warns that openly defying a god would be dangerous, so the three decide to go.

At the abandoned Waterland park, Grover flies over the fence with the winged shoes and helps Percy and Annabeth get inside. The trio finds fresh souvenir clothes, changes, and searches the park while discussing Ares's affair with Aphrodite and Hephaestus's history of humiliating them. At the bottom of the empty Thrill Ride O' Love pool, Percy and Annabeth find Ares's shield in a boat beside Aphrodite's scarf. Annabeth notices the Greek letter eta, realizes too late that the setup is linked to Hephaestus, and Percy trips an invisible wire when he grabs the shield.

Hephaestus's trap activates immediately. A golden net forms over the pool, cameras and spotlights announce that the scene will be broadcast live to Olympus, and mechanical spiders swarm out from hidden compartments. Annabeth is overwhelmed by terror because of her fear of spiders, Grover cannot tear open the net, and Percy realizes the trap was designed to disgrace Ares and Aphrodite. With time running out, Percy orders Grover to work the control booth and then uses his connection to water to force a flood through the pipes, washing away the spiders and sending the boat racing through the ride.

The boat shoots through the tunnel but heads toward chained exit gates and wrecked boats. Percy straps the shield to his arm, and Annabeth uses quick calculations to time their jump at the moment of impact. Grover catches Percy and Annabeth in midair and slows their fall enough for all three to survive, though they crash hard. After recovering, Percy sees that the cameras have followed them the whole time, realizes they have been used for the gods' entertainment, and decides they need to confront Ares.