A look at how the intense relationship between Carl Jung (Michael Fassbender) and Sigmund Freud (Viggo Mortensen) gives birth to psychoanalysis.

Keira Knightley's electrifying performance carries cerebral psychodrama.

As Sabina Spielrein, the troubled daughter of Russian doctors, Keira Knightley begins David Cronenberg’s A Dangerous Method with her contorted face pressed against the window of the carriage taking her to a Swiss mental hospital. With her jaw extruded and her eyes aflame, she screams and whimpers, laughing as orderlies carry her inside. It is 1904, the word ambivalent has just been coined, and the Zurich psychiatrist Carl Jung (Michael Fassbender) is ready to pursue the idea of 'the talking cure" that has been proposed by his Viennese elder, Sigmund Freud (Viggo Mortensen). It is the birth of psychoanalysis, and Spielrein is the lightning rod.

Since her breakthrough performance in Bend it Like Beckham 10 years ago Knightley has played at being a pirate alongside Johnny Depp and used her beauty as a monument to tragedy in Atonement, but her compelling performance for Cronenberg is something altogether more. Even when Sabina is deemed cured and studying to be one of the first psychoanalysts, her presence is electrifying – Knightley’s elongated frame almost convulses with the fierceness of the character’s personal and public passions, and it’s even enough to symbolically unclip the starched collar of Jung.

Christopher Hampton adapted his 2002 play The Talking Cure for A Dangerous Method, and one of Cronenberg’s achievements is to disguise how stage-bound the story still is. This is a film where the professional father and son – Freud and Jung – must fall out, and a great deal of it is contained in scathing letters they exchange. Much of the film is paired discussions between the three leads, and Cronenberg uses deep focus photography to make the foreground and background equally clear so that you can see how the exchange of ideas and opinions moves between individuals.

Mortsensen plays Freud as a wary, sometimes droll pioneer, as alert to the mental discord caused by the suppression of sexual desire as the hourly fee he charges patients. He encourages Jung, but is also somewhat jealous of the younger man’s wealth and comparative freedom; the film references the Jewish intelligentsia of pre-WWI Vienna that was tolerated but never fully accepted, and Freud’s fear of public outrage about his theories. When he sends another protégé, the neurotic and licentious Otto Gross (Vincent Cassel) to Jung, it’s as much for the former’s care as the latter’s temptation.

Gross encourages Jung to follow his lead and sleep with his patients, specifically Sabina, and Fassbender plays this straitlaced obsessive with attentive control. His Jung is not tortured, rather he’s decisive. When he acts on his desires he surrenders to them, and when rumours circulate the married father abruptly pushes her away. Both men are flawed enough that a schism, professional and personal, is assured, and the person who most advances their ideas is in fact Sabina. Her theories, including the approximation of the sex drive and the death wish, are the future, and she portends a century where women will pursue equality.

Cronenberg’s recent movies – A History of Violence, Eastern Promises – have been genre pieces that dwelt on the roles people play and how their lies can become permanent. A Dangerous Method purses this from a cerebral angle – the filmmaker who once blew up heads now wants to get them inside them – but it remains in debt to the great man of history theory, when the real catalyst is Sabina. This is a fine movie, composed and thoughtful to theme, but a further focus on the female protagonist could have made it revelatory and unsettling. You’ll want more of Keira Knightley as Sabina Spielrein.