Russell Partridge tells his wife Janet he murdered his six previous wives and that she has one day before he murders her, too. Janet can get no one to believe her except Holmes and Watson who must trap the killer before time runs out.
Sir Charles Farnsworth is found dead in his mysterious Farnsworth Castle. He had a clause inserted in his will that his death must be investigated by Sherlock Holmes. Holmes reveals traces of arsenic in the man's body and many suspects.
Sherlock Holmes investigates a strange story told to him by a shopkeeper, who claims to have been a member of the 'League of Red-Headed Men' until it unexpectedly dissolved.
A young boy asks for Holmes' help in finding his missing father. Holmes' investigation reveals the man is a gambler on the run from his creditors. The team makes the rounds of the seedy gambling underworld in search of the boy's father.