In the ever-escalating stakes of superhero TV, where the goal these days is to get trippier and trippier, nothing could out-trip Legion. In its excellent debut season, Noah Hawley turns the minor Marvel X-Men character into a lunatic fable, taking off from the original the way he took off from the Coen Brothers in Fargo. Dan Stevens is the mutant superhero who can't completely tell if he's got special powers or he's just touched in the head. (In the words of Pink Floyd, the band that looms over Legion as one its biggest influences, he's got a bad case of "There's someone in my head but it's not me.") Rachel Keller is great as his spooky girlfriend, the none-too-subtly named Syd Barrett. But the MVP has to be Aubrey Plaza, who gets to strut her villainness stuff as the fearsome Shadow King.