This is one of the weirdest films in Universal's series of mysteries based on Sir Arthur Conan Doyle's characters. It pits Sherlock Holmes (Basil Rathbone) against evil Professor Moriarty (Henry Daniell) and a beautiful hypnotist (Hillary Brooke) as he investigates the murders of women who are found with their right forefingers severed. The grindingly eerie music used to mesmerise the victims sounds a note of real unease, which not even the bumbling banalities of Nigel Bruce (as Dr Watson) can dispel. Rathbone always said that the restrained Daniell was his favourite Moriarty, and on the evidence of this film one can see why - with his air of cerebral containment and softly spoken precision, Daniell shows all too clearly the similarities of temperament between the master criminal and the Baker Street sleuth.

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.