Former ‘Downton Abbey’ star Dan Stevens has landed the lead role in 'Legion', an upcoming television series based on the X-Men franchise. The eight-part FX drama is set to debut in early 2017 and will also star Aubrey Plaza, Jean Smart and Rachel Keller.

Stevens will play David Haller who is described as ‘a man who may be more than human and who has struggled with mental illness since his teenage years'. Diagnosed as schizophrenic, David has spent years being in and out of psychiatric hospitals, but ‘after a strange encounter with a fellow patient, he is confronted with the possibility that the voices he hears and the visions he sees might be real.’

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The character made his X-Men comic book debut in New Mutants No. 25 in March 1985. In the comics he is the son of X-Men founder Charles Xavier and Israeli Holocaust survivor Gabrielle Haller.

Aubrey Plaza from ‘Parks and Recreation' will play Lenny, David's friend, while 'Fargo’s' Jean Smart will play Melanie, a therapist. Rachel Keller’s as-yet-unnamed character is rumored to be a mix of Rogue and Spyke, according to The Hollywood Reporter.

The series’ pilot episode was directed by ‘Fargo’ writer Noah Hawley, who will also serve as executive producer. “We’ve come to expect excellence from Noah Hawley and with Legion he has delivered another major creative achievement,” said FX original programming president Nick Grad.

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“Just as he did in reimagining Fargo, he is bringing an entirely new aesthetic and sensibility to the enormously popular and richly represented X-Men world. The pilot episode is stunning, driven by incredible performances from Dan Stevens, Aubrey Plaza, Jean Smart, Rachel Keller and the rest of the cast,” Grad added.