Sherlock Holmes investigates when young women around London turn up murdered, each with a finger severed. Scotland Yard suspects a madman, but Holmes believes the killings to be part of a diabolical plot.
In 1903, Doctor Huntington Bailey meets a friendly older lady during a train trip. She tells him that she is going to visit her brother Nick and his lovely young wife Allida. Once in New York, Bailey hears that his train companion suddenly died. Shortly afterward, he meets the strange couple and gets suspicious of Nick's treatment of his wife.
The famous Borgia Pearl, a valuable gem with a history of bringing murder and misfortune to its owner since the days of the Borgias, is brought to London, thanks in part to Sherlock Holmes. But before long the jewel is stolen, due to an error on Holmes' part, and shortly thereafter, a series of horrible murders begin, the murderer leaving his victims with their spines snapped and surrounded by a mass of smashed china.
When a woman is found dead with her throat torn out, the local villagers blame a supernatural monster. But Sherlock Holmes, who gets drawn into the case from nearby Quebec, suspects a human murderer.
Sherlock Holmes investigates a series of so-called "pajama suicides". He knows the female villain behind them is as cunning as Moriarty and as venomous as a spider. Based on "The Sign of Four" and the short stories "The Dying Detective", "The Final Problem", "The Speckled Band" and "The Adventure of the Devil's Foot".
Losing his memories of the last few days, neurologist Dr. Steele is told that his wife has been brutally murdered. Steele, aware of his conniving wife's infidelity, believes he may have been the killer and enlists the aid of his pretty nurse Stella to hypnotize him into recovering his lost memories.