Sherlock Holmes is called to investigate a murder: a man was found shot in a train car, with two bullets in his head. After much investigation Sherlock finds a hobo who was at a station as the train wheezed by. This man saw two men come in from opposite sides of a wagon and simultaneously fire their revolvers at a chap sitting right in the middle of the train car. Being a Newton acolyte, Holmes is a firm believer that simultaneity is a universal concept, and concludes that both men fired at the same time as an absolute fact. Inspector Lestrade (from Scotland Yard) manages to find both men, who are found guilty of the crime and die in the gallows.