In a dark and dangerous future, the mutant-hunting machines known as the Sentinels rule America with an iron fist. Almost all mutants and superhumans have been exterminated. Only a handful of imprisoned mutants remain to fight against their oppressive robotic overseers! Now Kate Pryde, former X-Man, must travel back in time and warn her present-day teammates of the coming danger--and hopefully prevent this horrible future from ever taking place!