Based on the Marvel Comics by Chris Claremont and Bill Sienkiewicz, Legion is the story of “David Haller” (Dan Stevens), a man who believed himself to be schizophrenic only to discover that he may actually be the most powerful mutant the world has ever seen. From childhood, David shuffled from one psychiatric institution to the next until, in his early 30s, he met and fell in love with a beautiful and troubled fellow patient named “Syd” (Rachel Keller). After Syd and David shared a startling encounter, he was forced to confront the shocking possibility that the voices he hears and the visions he sees may actually be real.