She seems to have a unique sense of time, for she realizes things have changed. She tells him the war they're in shouldn't be happening, and says the Ent-C is not supposed to be here. Picard goes to sickbay to talk to Garrett, who demands to know where she is (last she knew, she was fighting to rescue a Klingon outpost on Norendra Three). Picard informs her that she's 22 years into her future, and that the destruction of the outpost plunged the Federation and the Klingons into 20 years of war. (Data's analysis shows clearly that the -C will not survive if it returns.)
Meanwhile, Yar has befriended the only other surviving bridge officer of the -C, Lt. Richard Castillo, and the two go to Garrett with the ship partially restored. Garrett appoints Castillo liaison officer to the -D, and returns to her ship, over Bev's objections. Picard demands more evidence from Guinan, and refuses to send them back without a firm reason. Guinan cannot give any, but invokes their long history together to convince him that she doesn't make a stand like this unless she knows she's right. Picard agrees, and prepares to send them back, over the objections of most of the bridge crew (though Data does say that even if they are destroyed, it might be considered a "meaningful" act of honor by the Klingons and prevent the war anyway). Picard tells Garrett of his decision, and informs her privately that the war in the present is going badly (Starfleet Command is projecting defeat within 6 months). She agrees, and as Picard returns to the -D, Yar stays for a moment to say goodbye to Castillo.
Suddenly, one Klingon Bird of Prey decloaks and fires, shrugging off the -D's phasers, damaging the -C, and killing Capt. Garrett. Castillo asks permission to take the ship back himself, and though Riker objects, Picard grants it. After kissing Castillo goodbye, Yar confronts Guinan about the way Guinan's looked at her. Eventually, Guinan tells her that in the other timeline, she died an empty death. Yar then requests a transfer to the -C from Picard, telling him that she may at least be able to provide the ship with the extra seconds or minutes it needs to change history. Picard agrees, and Castillo welcomes Yar aboard.
As the -C prepares to enter the rift, three Klingon ships attack, and the -D is forced to remain and defend the -C. Although they manage to destroy one, the odds go against them, and after a containment field is damaged (coupled with a coolant leak), only two minutes remain until a warp-core breach. With 52 seconds until the -C enters the rift, the Klingons demand surrender, and Picard refuses, allowing his bridge to go up in flames first. The -C passes through the rift- and suddenly, everything is as it was. Guinan checks to see if all is well, then asks Geordi, "tell me about...Tasha Yar."