Penhallow is the last of his kind. The stone gargoyle--he'd prefer you call him a grotesque--fearlessly protects his Boston building from the spirits who haunt the night. But even he is outmatched when Hetty, his newest ward, nearly falls victim to the Boneless King, the ruler of the underworld.

Then there's Viola, the mysterious girl who keeps turning up at the most unlikely times. In a world where nightmares come to life, Viola could be just the ally Penhallow needs. But can he trust her when every shadow hides another secret? Can he afford not to?