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.

Genial shopkeeper Philip has to endure the constant nagging of a shrewish wife while he secretly yearns for a pretty young stenographer. When the henpecking gets to be too much, Philip murders his wife and manages to make her death look like an accident. A ruthless blackmailer and a low-key detective both discover Philip's secret, and he has to decide which of them poses the more dangerous threat.