"These apparently motiveless crimes are always the worst," said the inspector dolefully.
Charity Buntington''s husband describes his wife as the most lovely and inoffensive person, whom nobody would want to hurt. But someone enters their home in broad daylight, strangles her, then cuts off and takes away her right forefinger. Inspector Hopkins asks Sherlock Holmes to help him investigate the case, but Charity''s friend Aurora Jones is also a private detective, and wishes to help bring her friend''s murderer to justice. Holmes is impressed with Jones'' skills, and although Hopkins is reluctant, he agrees to let Miss Jones assist in the case under Holmes'' guidance.
A few days later, another woman is killed in exactly the same fashion. And then another. The press is in a frenzy. Holmes believes there is a pattern to the killings, but what it is no-one can determine. Slowly the clues accumulate, but so do the bodies. With Holmes leading the investigation, he, Dr. Watson, Inspector Hopkins and Aurora Jones all work together to discover the killer''s identity, but can they solve the mystery before another woman loses her life?
