Rosie Strange doesn't believe in ghosts or witches or magic. It's no surprise therefore when she inherits the ramshackle Essex Witch Museum, her first thought is to take the money and run. Still, the museum exerts a curious pull over Rosie. There's the eccentric academic who bustles in to demand she help in a hunt for the bones of the notorious Ursula Cadence, a witch long since put to death. And there's curator Sam Stone, a man about whom Rosie can't decide if he's tiresomely annoying or extremely captivating. Finding herself and Sam embroiled in a peculiar centuries-old mystery, Rosie quickly discovers that the secrets of the past come with their own real danger as a strange magic threatens to envelope them all.