In 1892, in the town of New Fiddleham, New England, many things are not what they seem at first glance. This time, the eccentric detective Jackaby and his assistant Abigail Rook have to investigate several supernatural cases at once. A mysterious death of a woman in a town neighboring New Fiddleham sets off a chain of frightening events: first, in the Gad Valley, the bones of a giant creature that were recently discovered vanish in an odd way; then another inexplicable murder occurs in New Fiddleham; and finally an unknown predator begins cruel attacks on animals and people. So the detective and his assistant open a hunt for the thief, the murderer, and the monster.