"Yesterday's Enterprise" is the 63rd episode of the American science fiction television series Star Trek: The Next Generation. It is the 15th episode of the third season, first airing in syndication in the week of February 19, 1990. Set in the 24th century, the series follows the adventures of the Starfleet crew of the Federation starship Enterprise-D. In this episode, the ship's crew must decide whether to send the time-traveling Enterprise-C back through a temporal rift to its certain destruction, to prevent damaging changes to their timeline. The plot for "Yesterday's Enterprise" was based on the merging of two story ideas—one featured the crew of the time-traveling Enterprise-C and the other the return of Denise Crosby, whose character Tasha Yar had been killed in the series' first season. Trent Christopher Ganino and Eric A. Stillwell rewrote the merged story to feature the character of Guinan more prominently. To complete the episode in time for sweeps, the final script was finished by a team of five writers. Filming of the episode lasted a week, with some elements of the script ultimately not included due to time constraints. In syndication, "Yesterday's Enterprise" outperformed most of the third season's episodes with a 13.1 Nielsen rating, the third-highest number for the series at the time. The episode is cited as a favorite by crew members and reviewers, and is widely regarded as one of the best episodes of the series. Plot The starship encounters a rift in spacetime. The crippled USS Enterprise-C, a ship believed to have been destroyed more than two decades earlier, emerges. The Enterprise-D undergoes a radical change from its previous timeline: it is now a warship, and the United Federation of Planets is at war with the Klingons. Neither Worf nor Counselor Troi are present, and Tasha Yar – killed years before – is running the tactical station. Only Guinan senses that reality has shifted, and meets with Captain Picard. She suggests that the Enterprise-C does not belong in their time and must return to the past. Picard, knowing this would be a suicide mission, refuses to give such an order based on Guinan's intuition alone. Captain Rachel Garrett of the Enterprise-C and her crew learn they traveled into the future. Garrett explains that they responded to a distress call from a Klingon outpost on Narendra III, and were attacked by Romulan starships. While his crew repairs the Enterprise-C and