Keira Knightly will star in "A Dangerous Method:" a film about a psychiatrist whose mentor is Sigmund Freud, and his patient. The sexually charged film is set in the early 1900s, and is directed by David Cronenberd ("Crash," "M. Butterfly").

Knightly plays Sabina Spielrien, a woman who enters a sexual relationship with her psychiatrist Carl Jung (Michael Fassbender). Viggo Mortensen ("The Road," "The Lord of the Rings") plays Jung's mentor, Sigmund Freud. 

The real Jung and Freud met in 1907 and became friends almost immediately. Jung described Freud as "extremely intelligent, shrewd, and altogether remarkable." Jung was Freud's protégé, but as the years went on their relationship began to deteriorate due to differences in their practice. The film is loosely based on the true story of the two psychiatrists.  

"A Dangerous Method" is due to hit theaters Sept. 2011. 

Watch the official trailer here