"Incident one hundred miles off the coast of Guadalcanal. Time: the present. The United States naval destroyer on what has been a most uneventful cruise. In a moment, they're going to send a man down thirty fathoms to check on a noise maker - someone or something tapping on metal. You may or may not read the results in a naval report, because Captain Beecham and his crew have just set a course that will lead this ship and everyone on it into the Twilight Zone."
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."Small naval engagement, the month of April, 1963. Not to be found in any historical annals. Look for this one filed under 'H' for haunting - in the Twilight Zone."