Rachel Keller as seen in "Legion"

Competition is booming between network television giants, cable channels and even streaming services, and the resulting diversity is making television great again. Big-budget special effects in shows such as "The Walking Dead" and innovative storytelling in series like "Stranger Things" have upped the ante for everyone in TV land, and FX has answered the call with one of the most ambitious TV shows to date.

Dan Stevens ("Downton Abbey") stars as a character from the Marvel universe in a new episode of "Legion," airing Wednesday, March 15, on FX. The series follows a 30-something man named David Haller (Stevens), who's been in and out of mental institutions since being diagnosed with paranoid schizophrenia as a teenager. In the Marvel Comics books from Chris Claremont and Bill Sienkiewicz, Haller -- a.k.a. Legion -- is the mutant son of Professor Charles Xavier, leader of the X-Men.

Creator and showrunner Noah Hawley worked with X-Men writer and producer Simon Kinberg on a concept for the series following the success of the first season of Hawley's "Fargo" for FX. This may be the first TV series connected to the X-Men film series, but that doesn't mean viewers should expect to see Wolverine or Professor X show up, at least not necessarily anytime soon. Before the show's February premiere, Hawley explained to Variety that Haller is surrounded by completely original characters in "Legion."

"None of the other characters that I've surrounded him with are from the comics," Hawley said. "It's sort of an invented world."

Worlds is more like it. The story moves back and forth through time, and seemingly through different realities, as Haller tries to figure out what's really going on. It's an exhilarating ride, and the audience is left to wonder which reality is the real one. His adventure began in a mental hospital where he lived with his BFF, Lenny (Aubrey Plaza, "Parks and Recreation"), until a beautiful new patient showed up and caught his eye. His infatuation with Syd (Rachel Keller, "Fargo") set off a chain of events that led him to escape from the institution and go on the lam from a mysterious group that knows he's actually a powerful mutant.

Luckily, thanks to Syd, he fell in with another group that appears to have his best interests at heart. Emmy winner and television icon Jean Smart ("Designing Women") is Haller's fairy godmother as demanding psychiatric therapist Melanie Bird, who wants to help him recall his past and take charge of his mutant powers, promising to make him whole again.

Other key players include scientist Cary Loudermilk (Bill Irwin, "Law & Order: Special Victims Unit"), one of Bird's specialists. Her team also includes Syd, savant Kerry Loudermilk (Amber Midthunder, "Longmire") and Dr. Poole (Scott Lawrence, "Fear the Walking Dead"), Bird's "memory specialist." Katie Aselton ("The League") portrays Haller's sister, Amy.

Dan Stevens stars in “Legion”

A stellar cast and slick special effects give "Legion" an arty, big-screen feel, and FX has thrown the full force of its publicity machine behind the series, which has been generating buzz since the development deal was announced in October 2015. Filmed in Vancouver, the show features visuals that include both modern elements as well as hints of 1960s design to reflect Haller's distorted view of reality. The Jan. 26 red carpet premiere in West Hollywood was even followed by a three-day "immersive art exhibit" that included pieces from Mark Murphy, Clemens Behr, Kumi Yamashita and David Flores.

Critics have been mostly positive towards the series, with many praising the chaotic pace and stunning visuals for pushing the boundaries of television. While some viewers may find the jumps through various times and places somewhat jarring or confusing, "Legion" seems to have broad appeal that goes beyond fans of the superhero genre.

Viewers won't likely see capes and tights as Haller continues his quest to control his powers and figure out what's really going on. So far, no one seems to miss the costumes, and "Legion" is breaking the superhero TV show mold. The series premiere, which aired Feb. 8, attracted more than three million viewers, including DVR viewings, and clocked in as the top cable drama in the key adults 18 to 49 demographic.

Fans and critics have been particularly keen on Stevens's performance as the conflicted Haller, a role he prepared for by talking to sufferers, psychiatrists and psychologists. The British actor is well known to fans of the hit ITV period drama "Downton Abbey," in which he played Matthew Crawley. His credits also include "The Guest" (2014) and "A Walk Among the Tombstones" (2014), but his biggest profile gig is yet to come. He stars as the Beast opposite Emma Watson's Belle in the upcoming live-action adaptation of "Beauty and the Beast," set to premiere in theaters March 17.   

Until then, check out Stevens as Haller, who returns to where it all began in a new episode of "Legion," airing Wednesday, March 15, on FX.