Three teenage descendants of Medusa, the once-beautiful Gorgon maligned in myth, must reunite and embrace their fates. Grace just moved to San Francisco and is excited to start over at a new school. The change is full of fresh possibilities, but it's also a tiny bit scary. It gets scarier when a minotaur walks in the door. And even more shocking when a girl who looks just like her shows up to fight the monster. Gretchen is tired of monsters pulling her out into the wee hours, but what can she do? Sending the minotaur back to his bleak home is just another notch on her combat belt. She never expected to run into this girl who could be her double, though. Greer has her life pretty well put together, thank you very much. But that all tilts sideways when two girls who look eerily like her appear on her doorstep and claim they're triplets, supernatural descendants of some hideous creature from Greek myth, destined to spend their lives hunting monsters...

Triplets narrate, teen descendants of Medusa. Warring factions among the gods of Olympus are coming; creatures of the Abyss are pushing into San Francisco; boys in their lives hide dangerous secrets. Tough Gretchen has fought monsters the longest, trains newfound sisters. Perfectionist Greer keeps her social calendar, faints from visions. Compromising Grace worries about missing brother Thane.

United triplets descended from Medusa must find gate between human and monster worlds, rescue aunts jailed under Mt Olympus. Greer must use her second sight, even though she hears gods argue in her mind. Grace wants to trust her adopted brother, Thane, but what is his secret? Orphan Gretchen has fought all her life, but now boys are helping - or are they?