 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.