In London, the Scotland Yard Detective Inspector Larry Holt is assigned to investigate a serious of deaths apparently in accidents. However, a further inquiry shows that all the victims are men without family and insurance policy released by the insurance agent Dr. Feodor Orloff and the beneficiary is a home for blind administrated by Prof. John Dearborn. When Henry Stuart is found drowned, his daughter Diana comes to London and helps Holt and his American partner Lieutenant O'Reilly in their investigation.