The Entire Wolverine Movie Story Finally Explained

X-Men: Days of Future Past opens in the year 2023, when mutants have been driven to near-extinction by the robotic Sentinels. However, a few mutants — including Logan (who miraculously has his adamantium claws back), Charles Xavier, Storm, and Magneto — have managed to elude the Sentinels long enough to form a plan. With the future already beyond repair, they decide to use Kitty Pryde's (Ellen Paige) mutant ability to send Logan's consciousness back to 1973 to stop the events that led to the creation of the Sentinels in the first place. They hope that, if he's successful, the timeline will reset, placing them all in an alternate (and safer) version of 2023. 

Using his 1973 body piloted by his 2023 consciousness, Logan joins forces with the younger Charles Xavier and his X-Men to prevent the assassination that paves the way for the Sentinel program. Although Logan succeeds in his mission, he's horribly injured in the process, with his mangled body sinking to the bottom of a lake. However, Logan's 2023 consciousness doesn't stick around long enough to learn how he survives. As soon as he changes the future, the Kitty who was holding him in the past vanishes, and he returns to an alternate 2023. In this new timeline, Logan realizes that his memories of the years since 1973 are no longer accurate. He's now a teacher in Xavier's school, where many of the X-Men who'd died in the primary timeline are now alive again, including Jean Grey.