Things can't get any worse. Legends are running riot. Half-hunters are out of control. Darkmouth has been taken away from Finn and Emmie, and Finn's dad Hugo - proud Legend Hunter - is washing dogs for a living. But something even more terrifying lurks beneath the surface: an ancient horror threatening both our world and the Infested Side. So scratch that. Things can get worse. Much worse. More than ever, Darkmouth is going to need a hero ... Sadly, all it's got is Finn.