The ultimate X-Men join forces with their younger selves in an epic battle that must change the past... to save our future! In Washington D.C., Trask unsuccessfully tries to sway Congress to gain support for his Sentinel program. Meanwhile, in Saigon, Mystique prevents William Stryker from appropriating a group of mutant G.I.s for Trask's research. Mystique investigates Trask's office and discovers he has been capturing mutants to use for his experiments.
