Percy's school, Yancy Academy, is on a field trip to a museum.
Percy's Pre-Algebra teacher turns into a monster and accuses Percy of being a thief. Luckily Mr.Brunner throws Percy a sword and he kills the monster.
Sally (Percy's mom)
Percy tells his mom what happened with Mrs.Dodds and she says that she'll take him and Grover somewhere safe. However, on their way there they get attacked by a half man/half bull monster that Sally calls a minotaur. The minotaur grabs Sally and she disappears into gold dust. Percy, in his anger, breaks of one of the monster's horns and kills him with it.
Percy returns to Camp Half-Blood, and finds the real lightning thief waiting for him!