When shy sixteen-year-old Helen Hamilton starts having vivid dreams about three ancient, hideous women and suddenly tries to kill a new student at her Nantucket high school, she discovers that she is playing out some version of an old tale involving Helen of Troy, the Three Furies, and a mythic battle.

As monsters walk the streets of San Francisco, unseen by humans, three teenaged descendants of Medusa, the once-beautiful gorgon maligned in Greek mythology, must reunite and embrace their fates.