Railway police arrest Watson despite his protest the blood came from a man he bumped into near the toilets. Holmes and William determine the victim, Trevor Redwood, is a jeweler who was inadvertently killed when he woke up in the middle of a robbery after being drugged. With Holmes following the physical evidence, William constructs a psychological profile of the killer. Following their methods, they both determine the killer is a porter who is unable to dispose of his bloody uniform. Holmes discovers blood on porter Eddie Hawthorn, but Hawthorn claims the blood is his own from an earlier accident...