In one month, two different eras of mutant history collide in one epic movie: "X-Men: Days of Future Past," directed by Bryan Singer and starring the casts of the original "X-Men" trilogy as well as 2011's "X-Men: First Class."

The final trailer for "Days of Future Past" is here, revealing more about Wolverine's mission to go back in time to the 1970s, and join forces with Charles Xavier and Erik "Magneto" Lensherr. The only problem: Xavier and Magneto are at complete and total odds, a far-cry from their future alliance. On top of that, the newly-paralyzed Xavier has seen better days, based on his shaggy-haired appearance.

Saving the future will be no easy feat -- but if anyone can do it, it's the fast-healing, adamantium-laced Logan.

"Days of Future Past" stars virtually everyone who has ever appeared in an "X-Men" movie before, and then some. Returning players include Halle Berry as Storm, Shawn Ashmore as Iceman and Ellen Page as Kitty Pryde. (Sorry, Anna Paquin; [article id="1719529"]no Rogue for you[/article].) New players include Omar Sy as Bishop, Adan Canto as Sunspot and Bingbing Fan as Blink.

And then, of course, there are the main characters: Hugh Jackman as Wolverine, Jennifer Lawrence as Mystique, Nicholas Hoult as Beast, and two different generations of Magneto and Xavier: the former played by Michael Fassbender and Ian McKellen, the latter played by James McAvoy and Patrick Stewart.

At a glance, it looks like "Days of Future Past" is the giant exclamation mark on a certain era of "X-Men" movies. But then again, plans are already in the works for "X-Men: Apocalypse" in 2016, as well as another solo "Wolverine" movie with Jackman and director James Mangold back on board.

In other words, even if the future of mutant kind is in jeopardy, the future of the "X-Men" franchise looks very active indeed.

"X-Men: Days of Future Past" hits theaters on May 23.