After Sherlock Holmes fires a revolver several times as part of an experiment, Dr. Watson finds a man who has fainted outside their flat after hearing the shots. The man is a shopkeeper named Wilson who has come to consult Holmes, and when he comes to, he tells his story. The assistant in his shop had drawn his attention to the 'League of Red-Headed Men', and had helped Wilson secure a position with the group. While his assistant watched the shop, Wilson was well paid for sitting in an office and copying out encyclopedia articles. When the league unexpectedly dissolved, Wilson decided to come to Holmes. The detective dismisses him brusquely, but after Wilson leaves, Holmes tells Watson that someone obviously wanted to keep Wilson away from his shop for some reason, probably as part of a scheme to commit a crime. Holmes and Watson proceed to the shop to investigate.