First Night: A Dangerous Method, Venice Film Festival

A Dangerous Method, scripted by Christopher Hampton from his play The Talking Cure (itself adapted from the book A Most Dangerous Method by John Kerr), is a deceptive affair.

It seems strait-laced and conventional by comparison with David Cronenberg's earlier movies – a handsomely shot costume drama set in Zurich and Vienna on the eve of the First World War.

However, scrape a little beneath the surface and you quickly realise that the Canadian is back exploring very familiar themes – hysteria, disgust, sexual and professional jealousy. For all its formal restraint, the film is just as subversive and as disquieting as predecessors such as Crash and The Naked Lunch.

The film boasts two assured performances from Michael Fassbender and Viggo Mortensen and a very brave, if uneven one, from Keira Knightley in her most challenging role to date.

Cronenberg's subject is the birth of psychoanalysis. The film chronicles the friendship and rivalry between Carl Jung (Fassbender) and Sigmund Freud (Mortensen). The key character is Sabina Spielrein (Knightley), an 18-year-old Russian diagnosed with hysteria.

Jung tries Freud's "talking cure" on her. He discovers that she was abused by her father and that she is a masochist, who takes extreme sexual pleasure in humiliation.

Spielrein is first seen being whisked away against her will to the sanatorium. She is writhing and twitching and looks like a vampire or witch being dragged to the stake.

Her anxieties are expressed in her wild and incontinent physical behaviour. Knightley portrays her as a quivering, hyper-sensitive hysteric. Her behaviour is in very marked contrast to that of the stolid doctors who tend her. Jung is "treating" Sabina but as he applies Freud's theories, his own assumptions about monogamy and repression are soon challenged. Vincent Cassel has a colourful cameo as Otto Gross, a fellow psychiatrist who is sick himself.

Gross is gleefully amoral. "Never repress anything" is his motto. Partly under his influence, Jung – who is growing increasingly distant from his pregnant wife – begins a sado-masochistic affair with Sabina.

Films featuring well-known historical figures can often seem arch and self-conscious in the extreme. Here, Mortensen has such immediate authority and swagger as Freud that we don't question his portrayal.

He is a sardonic and witty cigar-chewing patriarch, encouraging but also gently mocking Jung, whom he sees initially as a protégé. Fassbensder skilfully conveys inner doubts, his growing mysticism, his lust and his love for Sabina without ever showing any overt emotions at all.

Knightley has the most difficult role, playing a woman who is extremely highly strung. Her performance is courageous and moving.

Cronenberg's achievement is to have made "an action movie with ideas". The film may be very heavy on talk indeed but when the dialogue is as sharp and double edged as it is here, that is not a problem.