BEGIN SLIDESHOW Trippy new Legion promo and season 1 recap released FX has released a new promo for the upcoming new season of Legion along with a full season 1 recap in case you need a refresher! Check them out in the player below and look for the series premiere on April 3. RELATED: New Legion Season 2 Trailer Promises Mental Mutant Mayhem Based on the Marvel Comics by Chris Claremont and Bill Sienkiewicz, Legion follows the story of David Haller (Dan Stevens), a man who believed he was schizophrenic but discovered he might be the most powerful mutant in the world.