London is in a panic over a series of apparent "Pajama Suicides." Sherlock Holmes, however, is more inclined to believe that they are calculated murders. It is up to the detective and his partner, Dr. Watson, to discover the motive and the means of these crimes and to quickly unmask the murderer. Miss Adria Spedding is an intoxicating woman of character whom Holmes is convinced is behind the killings. A series of masquerades and deadly game playing ensues as Holmes and Watson enter a battle of wits with The Spider Woman.