Percy has been thrown out of school after school, and he has been hoping that this one would be different. Now, however, on the 6th grade field trip to the Metropolitan Museum of Art, Percy finds himself in trouble with the algebra teacher. She takes him deep into the galleries to discipline him, and, as she begins her reprimand, Percy watches in disbelief as her eyes become coals, her hands become talons and all in all, she just isn't human anymore. At the perfect moment his favorite teacher rolls in in his wheelchair and throws Percy his pen. The pen transforms itself into a sword, and Percy wields it in his own defense. Clearly not an ordinary field trip! Very soon Percy learns that his best friend is other-worldly and that his mother has been keeping a very important secret. Percy's fate is intertwined with the fate of the Gods. Other books in this series include The Battle of the Labyrinth and The Sea of Monsters.