Jason Grace awakens on a school bus which belongs to the Wilderness School, unable to remember anything about his past. He is next to Piper McLean, his apparent girlfriend, and Leo Valdez, his apparent best friend. All three are part of a class field trip to the Grand Canyon. After they arrive there, a classmate, Dylan, turns into a storm spirit and attacks the trio and their trip leader, Coach Gleeson Hedge. In the ensuing fight, Jason battles the spirit and surprises everyone with his powers. Hedge is revealed to be a satyr and is captured by the storm spirit as it flees. A flying chariot with two demigods appears on the scene. The female demigod, Annabeth Chase expresses her frustration upon seeing that her missing boyfriend, Percy Jackson, is not there as she had hoped, as he has been missing for three days without a trace. Jason, Piper, and Leo are told that they are Greek demigods and are taken back to Camp Half-Blood. There, Leo is revealed as a son of Hephaestus, Piper as a daughter of Aphrodite, and Jason as a son of Zeus. Juno, the Roman form of Hera, appears to Jason and tells him he is also her champion.
