Twelve-year old Johnny Dixon and his friend Professor Childermass look for the hidden will left by an eccentric cereal tycoon, Mr. Glomus, who wished to make life difficult for his heirs after his own death by suicide. Although the professor warns him to stay away from the Glomus mansion, Johnny can't resist a challenge. Soon he's alone in the deserted house...with one of the undead at his heels!