The ultimate X-Men ensemble fights a war for the survival of the species across two time periods in 'X-Men: Days of Future Past'. 'X-Men: Days of Future Past' takes its name from the comic book by Chris Claremont and John Byrne. Though official plot details are currently under wraps, the original story shows the last remaining members of the X-Men living in an apocalyptic future where giant robots called Sentinels stalk the Earth and mutants are hunted down.The beloved characters from the original “X-Men” film trilogy join forces with their younger selves from “X-Men: First Class,” in an epic battle that must change the past – to save our future.