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.
The heirs to a family fortune are required to attend a seance at the spooky old family mansion. However, throughout the night members of the family are being killed off one by one.
The stooges are witnesses at a trial where their friend, a dancer at a nightclub where they are musicians, is accused of murder. The stooges manage to disrupt the proceedings but save the day when they discover the real murderer's identity.
After a famous criminal is run over and killed by a milk wagon, Insp. Lestrade finds a mysterious coded note in the man's clothing. He asks Holmes to decipher it, and Holmes' subsequent investigation leads him to assume the dead gangster's identity and he follows a trail of clues to Paris