Percy wakes in Camp Half-Blood after two days of recovery, remembering fragments of Annabeth feeding him and urgently asking what will happen at the summer solstice and what was stolen. On the porch, Grover confirms that the Minotaur attack was real by returning one of its horns. Percy realizes that Sally is truly gone, but Grover blames himself for failing to protect Percy. A magical drink that tastes like Sally’s homemade chocolate-chip cookies restores Percy’s strength enough for Grover to lead him to meet the camp leaders.

As Percy crosses the grounds, he sees a camp filled with Greek-style buildings, orange-shirted campers, satyrs, and even winged horses. Grover introduces the camp director, Mr. D, Annabeth Chase, and Percy’s former Latin teacher, Mr. Brunner. Mr. Brunner reveals that his name at school was a disguise and tells Percy to call him Chiron. Annabeth, who has been caring for Percy, coolly notes that Percy drools in his sleep before leaving to prepare his cabin.

During a pinochle game, Chiron explains that he and Grover watched Percy at Yancy because they suspected Percy was special and might be ready for Camp Half-Blood. Percy presses them for answers, and Chiron tells him that the Greek gods are real. Mr. D reacts angrily to Percy’s skepticism, warns him not to use divine names casually, and casually performs magic by changing a goblet of wine into Diet Coke. Chiron explains that Mr. D is Dionysus, punished by Zeus and forced to run the camp, and Dionysus briefly reveals enough divine power to frighten Percy into obedience.

After Dionysus leaves with Grover to discuss Grover’s failed assignment, Chiron answers more of Percy’s questions. Chiron says that Olympus has not vanished but moves with the "heart of the West," which is now in America, so the gods live here as Western civilization shifts. Percy asks who Chiron is and who Percy himself might be. In response, Chiron rises from what Percy thought was a wheelchair and reveals his true form: a centaur. He then leads Percy toward cabin eleven and the rest of camp, leaving Percy with the overwhelming knowledge that mythology is real and that he belongs inside it.