In 2344, Romulans attacked the Klingon outpost at Narendra III; the Enterprise answered the distress call. The Enterprise engaged the Romulans, facing four warbirds. An exchange of fire between the Starfleet ship and the Romulans catalyzed the formation of a Kerr Loop, disrupting the space-time continuum. The Enterprise travels through the loop into the mid-2360s, creating an alternate timeline in which history records that the Enterprise-C went missing and the Romulans destroyed the outpost. This series of events leads to a Federation-Klingon war, which in the 2360s the Federation is losing.
Displaced in time, the Enterprise-C encounters the Enterprise-D. The latter manages to repair most of the earlier ship's damage and treat its injured crew, 125 of whom have survived. Influenced by the time-sensitive Guinan, Captain Jean-Luc Picard persuades Garrett to return through the disruption, hoping that the sacrifice of one ship in defense of the Klingon outpost will prevent the war. Garrett is killed during a Klingon attack before the ship can restore the timeline. The surviving crew, under the command of helmsman Lieutenant Junior Grade Richard Castillo, along with the future timeline's Lieutenant Tasha Yar, take the ship back into the disruption. This act returns the Enterprise-C to Narendra III in 2344 at the moment she had previously disappeared. The timeline is restored; the Federation and Klingons are not at war, and the Enterprise-C is destroyed.
The Romulans captured several Enterprise-C survivors, about which Starfleet heard unconfirmed rumors. Tasha Yar was one such survivor, and she went on to bear a Romulan general's child, Sela. Yar is executed after she is caught attempting to escape with four-year-old Sela.