X-Men: Days of Future Past takes place in a bleak future where mutants have been nearly eradicated, and Professor X and Magneto just can't stop dwell on how hard they fucked things up. They used to know Kevin Bacon, man. But as is said, no point in dwelling on the past, because you can't change it. Unless you can change it, as Professor X apparently can. So, he decides to do that, sending a grizzled Hugh Jackman back in time to tell everyone to do a better job with teamwork in fighting the mutant-killing robots. Oh yeah: also, there are mutant-killing robot sentinels now because of Peter Dinklage.
Here's the latest trailer. The ruined skyscrapers and lone villain in a football field are hints that this is just as serious as a Dark Knight Rises, everyone: