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.
Holmes and Watson board a passenger train bound from London to Edinburgh, to guard the Star of Rhodesia, an enormous diamond worth a fortune belonging to an elderly woman of wealth; but within the first hour of the trip, the woman’s son is murdered and the diamond stolen and any of the passengers in their car could be the killer thief.
Dowdy Sylvia accepts her boss’ marriage proposal, even though he only asked her to avoid marriage to another woman. As a wealthy wife, Sylvia changes from ugly duckling to uninhibited swan and even contemplates having an affair with a man she meets during a trip to Paris.
Ann Harding plays a lovely but somewhat naive young woman who goes on a European vacation after winning a lottery. Swept off her feet by charming Basil Rathbone, Harding finds herself married before she is fully able to grasp the situation. Slowly but surely, Rathbone’s loving veneer crumbles; when he casually asks Harding to sign a document turning her entire fortune over to him, she deduces that her days are numbered.