 When a landlady finds one of her tenants murdered, Inspector Hornleigh is sent to investigate. Hornleigh s assistant, Sergeant Bingham, soon finds an attaché case that had been stolen from the murdered man. When Hornleigh examines the case, inside it he finds a bag that was used to carry important government documents. The documents have been taken, and to make things even more confusing, a duplicate of the stolen bag soon turns up.