Here's the first trailer for 20th Century Fox's X-Men Days of Future Past.  Watch it after the jump.

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.” 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.

Hmmm I still can't figure out how faithful this adaptation to the source material.  The story is still foggy and the trailer looks just like a montage of footage.  The only clear detail we got is how Xavier (the old one) seek the help of Logan to convince and teach his younger self.  We got the chance to see most of the old X-Men and finally some of the new ones.

L-R: Omar Sy as Bishop, Adan Canto as Roberto da Costa/Sunspot, Booboo Stewart as James Proudstar/Warpath and Bingbing Fan as Clarice Ferguson/Blink

Surprisingly thereis still no Sentinel footage but  I'm looking forward to see more of that on the next trailers. Be ready as the mutants return in May 21, 2014, X-Men Days of Future Past is from Marvel Studios to be distributed by 20th Century Fox through Warner Bros.