The Film Noir Encyclopeia lists Stranger as the first true film noir. It's not hard to see why. The lengthy interior dialog, the grotesque dream sequence, and the expressionist lighting, all bespeak the arrival of a noir universe. Over the next ten or so years, this European style would encompass a number of film genres, seeping even into that most American of all, the Western ("Blood on the Moon", "Roughshod", et al.). I can only imagine how 1940's audiences greeted this abrupt departure on first showing.
Except for Lorre, it's a no-name cast, although Tallichet makes for a charming leading lady with a captivating smile. The absence of a familiar face (John McGuire) in the male lead actually helps. Instead of seeing a celebrity in a starring role, we see an unknown that might even be us. And so, both he and we are drawn deeper into a nightmarish web of guilt. Notice how the lighting becomes steadily darker as McGuire's anguish deepens, with shadows that are almost all appropriately angular and threatening. Also, note director Ingster's very real feel for the ethnic vibrancy of a New York street even though it's recreated on an RKO sound stage. This sense of a community life outside the third floor makes for an interesting contrast with McGuire's growing inward turn.
Too bad the script fails to match the visuals in imagination and stylishness. It's really pretty conventional, except for the nicely ironical twist of having the jury-trial deficiencies turned back upon McGuire in the dream sequence. Good thing they had Lorre outfitted with buck teeth and doing an exquisitely loony menace, because the climax itself is very unimaginatively staged. It could have come from a thousand other more ordinary films. Anyway, for fans of noir and movie historians, this obscure little production remains essential and entertaining viewing.