More cerebral than shocking, David Cronenberg’s “A Dangerous Method” explores the falling out between father of psychiatry Sigmund Freud (Viggo Mortensen) and his most famous follower, Alfred Jung (Michael Fassbender). Their split is precipitated by a woman — a hysterical patient of Jung’s who becomes the married doctor’s lover as well as woman as a noted analyst herself. Freud fears the scandal will give psychotherapy’s enemies ammunition.

Jung also increasingly questions Freud’s insistence that all neurosis is rooted in sexual issues in this very talky film, much of which is given over to the reading of letters but is compelling nonetheless, and often drily funny. It’s an uncommonly good-looking movie with great period detail — it’s set in Vienna and Switzerland, where Jung works at a private clinic, during the early part of the 20th century.

Fassbender, who has the larger part, and Mortensen do a fine job in this adaptation of a play and book. Top-billed Keira Knightley goes a bit over the top as the woman, focusing way too hard on grimacing and her Jewish-Russian accent, especially in the early part of the movie.