The Knocking on the Door

First appearing in Collier's on June 28, 1913, then on July, 1913 in The Storyteller. It later made up the final chapters 27-30 in The Insidious Dr. Fu Manchu.
In the showdown with Fu Manchu, the police inspector helping Nayland Smith becomes a victim and to save his life, Smith must make a deal with the Devil Doctor.