Captain Beecham and his crew are investigating a sunken submarine, when they pick up a tapping sound coming from inside it. Chief Bell sees the ghosts of young seamen in the corridor, and he confesses to the ship's doctor that he was on the sub, and it was his fault it sank. He thens jumps overboard and drowns. Later, a diver reports that a section of periscope was loose and that was the source of the tapping. However, one of the dead crewmen did have a hammer in his hand.