Meet Grace, who just moved to San Francisco. It's a tiny bit scary starting over, but it gets scarier when a minotaur walks in the door. And even more shocking when a girl who looks exactly like Grace turns up to fight it. . . Gretchen is fed up of monsters pulling her out into the small hours, especially on a school night. Getting rid of a minotaur is just another notch on her combat belt, but she never expected to run into a girl who could be her double in the process. . . Greer has her life pretty well put together, thank you very much. But everything tilts sideways when two girls who look eerily like her appear on her doorstep and claim they're all sisters. . . These three teen descendants of Medusa must reunite and embrace their fates!