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.