Lord Montcalfe, a well-known Egyptologist, is missing, believed by the police to have committed suicide. His daughter, Elisabeth, insists that he is still alive and calls upon her fiance's cousin, Sherlock Holmes, to prove her theories. Arriving at the manor, Holmes finds that Lord Montcalfe was suffering from a deep paranoia. It seems he had made a terrible mistake and triggered what he believed to be a mummy's curse. Trying to shield himself and others from that curse, he had booby trapped his own home with elaborate locks, some of which were designed to kill anyone who tried to tamper with them.