Marvel's "X-Men" spin-off TV series "Legion" on FX has cast "Fargo" standout Rachel Keller in a lead role.

As this exciting bit of news comes down the pipe, there is even more reason to believe that "Legion" is going to be an outstanding show.

According to Deadline, Keller gave such an incredible breakout performance on "Fargo" Season 2, that series creator Noah Hawley has cast her in his "Legion" project.

The basic premise for the series is the story of Charles Xavier's son, David Haller. The character, who is also the Marvel superhero "Legion," tragically endured hardship as a young man, leading him to believe that he had a mental illness. Haller had visions, and doctors at the various mental institutions that imprisoned him diagnosed him as a schizophrenic.

The character is made unique and tragic by this back story, permanently scarred by spending his entire childhood and young adult life thinking he was crazy and that his visions were not real.

That all changed when he had a chance encounter with a woman (Keller) who convinces him that he is not really crazy after all. Instead, he is merely a mutant with a special ability, much like his father. In addition to the visions, it also turns out he has inherited his father's other abilities as well.

Keller's role in this film as the female lead may be somewhat controversial. Although she latches on to Haller, it is unclear if she intends to use him for good or to take advantage of his abilities for herself.

Fans already know the character is opportunistic, a woman seemingly always able to find the leverage she needs to survive in the world. Although she may not have imperial ambitions of world domination, she certainly does seem to be ultimately motivated by her own survival, which may seem selfish, at least in the beginning.

There has been no word yet when the show will premiere on the cable network.