The first film in the series is Polanski's English-language debut, Repulsion (1965). Catherine Deneuve stars as Carole, a disturbed young woman who becomes increasingly paranoid and hysterical the longer she's left alone in her London apartment. She finds her relationship with men moving from strained to dangerous and violent, quickly including rape and murder. The terror physically manifests itself as the apartment's filth and decay -- and mounting dead bodies. Tight shots and limited sets make the audience share the anxiety and paranoia of Carole. If anything, the film's only flaw is that it's too effective, too anxiety-producing to merit repeat viewings.
Although second in the series, Rosemary's Baby is by far the most well known. It's no surprise with the famous names attached: William Castle produced it, and the all-star cast includes Mia Farrow and John Cassavetes. Similar to Repulsion, Rosemary's Baby tells the story of a young woman whose relationship with her neighbors -- and with reality -- becomes tenser and tenser. Is she just paranoid as her maternal instinct is kicking in, or is there something more devious happening in her New York City apartment building? I assume that many find Rosemary's Baby to be a more satisfying viewing experience than its predecessor because of its tangibility; whereas Repulsion left you guessing about the goings-on around Carole, Rosemary's Baby provides definitive answers to the viewers' questions. This doesn't make the film any less terrifying; if anything, sometimes it's knowing what people are capable of that's most horrifying of all.
The apartment trilogy ends with a more masculine turn in The Tenant (1976). Polanski himself stars as Trelkovsky, a painfully shy diplomat who moves into an unusual Paris apartment. His natural curiosity leads him to investigate what happened to his room's previous tenant -- an investigation that reveals a suspicious suicide under questionable circumstances. Did the previous tenant really kill herself, did someone else throw her out of the window, or was she somehow compelled to throw herself out the window as her only means of egress? In a way, this female tenant could be seen as an extension of Carole from Repulsion -- a young woman devastated and tortured by urbanity. As Trelkovsky digs deeper into the mysteries surrounding his apartment, he becomes increasingly convinced that his neighbors are plotting his demise. Like the first film in the series, The Tenant returns to ambiguity, never quite revealing whether or not the neighbors are guilty like they are in Rosemary's Baby. However, this vagueness works to the film's advantage, as Trelkovsky takes matters into his own hands.
When viewed separately, each of the films in Polanski's apartment trilogy amplify the isolation and paranoia of modernity. Combined together, they show how this stress is global, stretching beyond countries, beyond gender, beyond class. No one can be trusted -- least of all yourself.