'X-Men: Days Of Future Past' Trailer: Watch Now!

The whole gang is back together for an epic sequel that will bring together two timelines.

For the first big "X-Men" movie since "The Avengers" conquered the world, characters from the series' two timelines are coming together to avoid one very bad future.

The newly released first trailer for "X-Men: Days of Future Past" spends the most of its two-minute runtime setting up the complex, time-bending story that will connect the world of Bryan Singer's "X-Men" featuring Patrick Stewart and Ian McKellen to the "First Class" world inhabited by their younger selves, played by James McAvoy and Michael Fassbender, respectively.

The key to all of this is the immortal Wolverine, played once again by Hugh Jackman, making his seventh appearance as the self-healing character.

When an apocalyptic war against the mutants breaks out, spelling the end for the gifted individuals, Professor Xavier and Magento are once again forced to team up for the betterment of mutant-kind. Their plan is to send Wolverine back to the 1960s, where he may be able to change the events of the past in order to prevent a disastrous future.

That future is the result of mostly one man, Bolivar Trask. The inventor of the enormous, mutant-hunting sentinels that brings about the dire circumstances is played here by "Game of Thrones" scene stealer Peter Dinklage.

"X-Men: Days of Future Past" brings essentially the entire casts from both sets of movies. Halle Berry, Ellen Page, Anna Paquin and many others are back from the Bryan Singer movies, while Jennifer Lawrence, Nicolas Hoult and more are back from "First Class." The new film also adds a number of new actors in addition to Dinklage, including Evan Peters as Quicksilver, Omar Sy as Bishop and "Twilight's" Booboo Stewart as Warpath.

"X-Men: Days of Future Past" opens in theaters on May 23, 2014.