Full story
In 2023, the world is in ruins. Robots called Sentinels hunt mutants and any human who might have mutant children. What's left of the X-Men is in hiding. In Moscow, a group with Kitty Pryde, Colossus, Bishop, Blink and others comes under attack. They only survive because Kitty can send Bishop's mind a few days into the past to warn the group before the strike.
At a temple in China, they meet up with Storm, Wolverine, Xavier and Magneto, now allies. Xavier explains where it all started: in 1973, Mystique killed scientist Bolivar Trask, creator of the Sentinels. She was captured, and her DNA let them build robots that adapt to any power. The plan is to send someone back to 1973 to stop the murder. Only Logan can survive a trip that long, thanks to his healing factor.
Logan wakes up in his 1973 body. At the mansion, he finds a young Charles, drunk and lost, taking a serum from Hank McCoy that gives him back his legs but takes away his telepathy. Erik is locked up under the Pentagon, accused of killing Kennedy. With help from a speedy kid, Peter Maximoff, they bust Erik out in a slow-motion jailbreak. In Paris, at the Vietnam peace talks, they stop Mystique from killing Trask. Erik tries to kill her to settle things for good, misses, and the fight happens in front of the cameras. The world sees mutants in action, and President Nixon approves the Sentinel program.
Charles quits the serum. Through Logan's mind, he talks to his future self and gets his hope back. Using Cerebro, he finds Mystique. Erik, meanwhile, laces the Sentinel prototypes with steel and takes control of them. In Washington, at the robots' unveiling, he lifts an entire stadium and drops it around the White House, throws Logan into the Potomac River and rips out the bunker with Nixon inside.
In the future, the Sentinels storm the temple and kill nearly everyone. In the past, a disguised Mystique takes Erik down with a plastic gun. She aims at Trask, but Charles asks her, mind to mind, not to do it. Mystique spares Trask in front of the world, and a mutant saving the president kills the program. The dark future is gone. Logan wakes up in 2023 at a thriving school, with Jean and Scott alive. Back in 1973, his body is pulled from the river by William Stryker, who is really Mystique. After the credits, in ancient Egypt, a crowd hails En Sabah Nur, who raises pyramids with his mind.