A man is seen standing aboard the deck of a British cargo liner crossing the Atlantic in 1942. The man's name is Carl Lanser and he appears disoriented, with no idea of how he got aboard or who he really is. Later, sitting with the captain and several passengers, Lanser dismisses fears of the ship being hunted by a U-boat "wolfpack" with an unusually-comprehensive knowledge of submarine warfare tactics. He is unable to explain how he knows any of this and recalls only that he was born in Germany but says that he finds the ship, its crew and passengers oddly familiar. When called to the bridge by the captain he cannot provide proof of his identity. Still confused, Lanser is sent back to his cabin with a steward, where he finds a Kriegsmarine officer's cap among his possessions with his name written on the inside. The captain is forced to stop the ship for repairs when the overworked engines break down at 12:05. Lanser becomes increasingly restless, haunted by an inescapable sense of impending doom. Convinced that everyone aboard the ship will die at 1:15, Lanser eventually panics and runs through the passageways, attempting to raise an alarm. He suddenly finds the ship is mysteriously empty and when he finally locates some of the passengers, they silently stare at him as he desperately tries to convince them to abandon ship and then they suddenly vanish. At exactly 1:15, as a searchlight illuminates the ship. Lanser watches in horror as a surfaced U-boat, commanded by a Captain lieutenant Carl Lanser, opens fire. The ship quickly sinks, leaving no survivors. Some time later, Captain Lanser is in his cabin aboard his U-boat, recording that night's kill. His second-in-command, Lt. Mueller, is deeply troubled by the vicious and cruel actions they have undertaken, not warning the peopleon board the ship before firing upon them, and wonders "if we are not all damned now". Lanser dismissively says he is sure the British Admiralty thinks so, but Mueller clarifies that he meant damned in the eyes of God. Despite Lanser's skepticism and sarcasm, Mueller grows more convinced that the crew of the U-boat may one day answer for their crime by reliving the act for all eternity. Granted his own private hell as the man who ordered the massacre, the former U-boat commander re-materializes on the deck of the ship and the nightmare begins again...
In the first 18 episodes, Serling only had one minor conflict with CBS regarding episode content. In an interview with Mike Wallace on September 22, 1959, Serling said, "We changed, in eighteen scripts, Mike, we have had one line changed, which, again, was a little ludicrous but of insufficient basic concern within the context of the story, not to put up a fight. On a bridge of a British ship, a sailor calls down to the galley and asks in my script for a pot of tea, because I believe that it's constitutionally acceptable in the British Navy to drink tea. One of my sponsors happens to sell instant coffee, and he took great umbrage, or at least minor umbrage anyway, with the idea of saying tea. Well, we had a couple of swings back and forth, nothing serious, and we decided we'd ask for a tray to be sent up to the bridge. But in eighteen scripts, that's the only conflict we've had." In the 1960 issue of Broadcasting, Serling complained: "You can't 'ford' a river if it's sponsored by Chevy; you can't offer someone a 'match' if it's sponsored by Ronson lighters." The Twilight Zone Companion joked that it was a good thing the sponsor did not realize that people could drink water, or else the episode would have happened on dry land.
