It's 2055, and America is ruled by mutant-hunting Sentinels. Aged Wolverine meets two younger mutants, who are attacked by Sentinel robots, and after that - Bishop, a mutant who works for Sentinels, hunting other mutants. Bishop captures all three and brings them to disposal center, only to find out that he is not needed anymore and will be disposed of, too. Joining forces, Wolverine and Bishop break free and manage to reach Forge's secret laboratory, where a working time machine is located. Forge has a theory that by preventing an assassination in the 1990's, it is possible to change the future. Wolverine plans to go back to the past and kill the assassin, but Bishop takes his place, claiming that he's younger and that the assassin's was one of the X-Men, Wolverine's old friend, so it would be hard for Wolverine to pull the trigger.
After he moves to the past, Bishop can't remember the details of his mission. He only knows that he needs to stop the assassin... and it is one of the X-Men.
— Description from Comic Vine community (comicvine.gamespot.com).
