On October 31, 2161, Tucker, along with Chandler Masterson, has selected the films for Halloween week. Apart from wanting to enjoy a few horror movies, Trip also wants to possibly find some female companionship. T'Pol and Hoshi Sato are both exes, and so they are both out. Amanda Cole seems a likely prospect.
At the same time, Malcolm Reed is off the ship, as he and Lili O'Day are having their first child. Declan Reed is scheduled to be born via cesarean section. Furthermore, because the ship is about to be decommissioned, Captain Archer has asked for full reports on everything that worked, and everything that did not, and puts Trip in charge of the overall draft report. Archer also reveals that he will be getting a new ship, the DC-1500, the USS Zefram Cochrane.
Travis Mayweather, who has not been promoted during the mission, is concerned that he will not be asked to pilot the Cochrane. When asked to join them at Movie night, he declines, intending instead to work on the report. Tucker heads to the film alone.
While watching John Carpenter's Halloween, with Cole, Phlox, Masterson and Aidan MacKenzie, the audience begins talking about warfare, and how horror movies can desensitize one to violence. Before he has a chance to comment, Trip suddenly disappears, and wakes up in Upper Bavaria, in Germany, in 1945. He, along with Herbie Shapiro, Stanislaus Kuzawa, Brendan O'Shaughnessy, Antonio Martinelli and Sergeant Randall McCoy, is a part of the American troops tasked with liberating the Dachau concentration camp.
Meanwhile, in 2367, Wesley Crusher, Data and Geordi La Forge are trying to figure out what happened to a static Warp bubble, as it appears to have disappeared after the Traveler rescued Beverly Crusher (TNG: "Remember Me").
On the 2161 Enterprise, scans are taken, but no one can find Tucker. In 2367, the investigation goes to historical documents. Aidan MacKenzie has a log entry, and is identified in his official Starfleet records as having eventually risen to the rank of captain. And T'Pol's great-grandchild has a personal log entry which refers to T'Pol having reminisced about the 2161 incident, recalling it when the USS Enterprise (NCC-1701) encountered the Eminians (TOS: "A Taste of Armageddon").
As Tucker is retrieved by the Traveler, his compatriots have decided that they will confirm reports to anyone who asks, that they saw the Holocaust first-hand. The Traveler confirms that they became staunch opponents of Holocaust deniers. As for Tucker, he destroys all of his horror memorabilia, except for a small figure of Frankenstein, and tells T'Pol what has happened, thereby completing the time loop.