An actress named Elisabeth (Liv Ullman) suddenly falls silent. She tired of playing roles, on stage, in life, no longer able to respond to the horrors and banalities of the world with idle politesse. Alma, her nurse (Bibi Andersson) is seemingly a chipper young woman, keeping up a stream of cheerful chatter as the two share a summer cottage. Eventually her good nature begins to elicit smiles and nods from her patient. But speaking into the void changes Alma more radically, especially after she recalls a hot sexual adventure (it is one of the movies’ great erotic tropes; you can see what happened even though the incident is recounted in purely verbal terms). Eventually, Alma turns into a version of Elisabeth, full of disgust and self-loathing. This story is presented as a film-within-an (unrealized)-film and it constitutes Bergman’s most austere masterpiece—his camera placements and editing have a simple rightness that belies the complex and enigmatic psychologies he is exploring. It is perhaps a movie none of us will ever fully understand, but the effort to do so is always at once unsettling and hypnotizing.