Summary

The book opens with Percy’s mother driving him, Annabeth, and Thalia towards an old castle that Percy identifies as Westover Hall, a military school. Percy reveals that he and the two girls are responding to some sort of distress call from his best friend, Grover. Percy and the others have come equipped with a number of weapons that they have kept hidden. The group heads into the school, running into two teachers who immediately start to question them. Thalia snaps her fingers and uses a power she calls the mist to magically charm one of the teachers into believing that they are students there. Percy is discouraged that Chiron never taught him this ability.

Grover arrives and pulls the group away from the teachers and into a dance going on at the gym. He reveals that he was sent to the school to...