In many ways, "Notorious" is the most quintessentially Hitchcock film.
The voyeurism that marked Alfred Hitchcock's movies is in clear evidence, with the many extreme close-ups and tracking shots, which were highly unusual in 1946 American cinema. There's one shot of Cary Grant and Ingrid Bergman embracing, and the camera slowly rotates around their heads -- a trick Hitchcock would use again, for example in his masterpiece "Vertigo." The overall effect in this movie is of following a subject, or being followed. Since it's a movie about espionage, it gives the audiences an unsettled, borderline paranoid mood.
There's also the classic use of the MacGuffin -- an object or other plot device that is used to drive the story, but which remains ill-defined or whose importance is never really made clear. It doesn't really matter what it is, in other words, only that everyone wants it. Hitchcock's films were replete with microfilm or sinister powders or such things that had the main character being chased around nilly-willy. In "Notorious" the MacGuffin is bottles of wines that turn out to contain a mysterious black sand.
And the misogyny that was often part and parcel of Hitchcock's work was never stronger than in "Notorious." Bergman plays Alicia Huberman, a German-American playgirl who is used as a Mata Hari by intelligence agent Devlin (Grant) to infiltrate a Nazi cel in Rio De Janeiro. Devlin, who recruits her after her father is convicted as a traitor, is at first repulsed by her constant boozing and loose morals. But he eventually falls for, only to learn that his assignment is to use Alicia as bait to lure out Alex Sebastian (Claude Rains), one of the Nazi co-conspirators.
Grant's performance is particularly icy and cruel, as opposed to his usual cocksure charm. At one point he admits that he's always been afraid of girls -- something feminist film theorists have had a field day with.
There's one great scene where Alicia is meeting with Devlin at a horse race to update him on her snooping, and she playfully tells him, "You can add Sebastian's name to my list of playmates" -- a not-at-all subtle indication that she has slept with him. The look that comes over Grant's face, one of anger and humiliation, quickly sours into an image of pure contempt.
Devlin's associates (the redoubtable Louis Calhern plays Devlin's boss) also speak contemptuously of Alicia, even though she's supplying them with invaluable intelligence about their enemies, because she's using sex to get what she wants. It goes without saying that these gentlemen would not be so quick to disparage one of their own employing the same tactics. When Alicia agrees to marry Sebastian to further the ruse, they view it only as an opportunity for them to dig up dirt on their foes.
Claude Rains had one of those truly magnificent film careers, nearly always as a supporting man (he was nominated for the Oscar four times, including this film, never winning) but occasionally in the lead. His portrayal of Sebastian is most interesting -- he is never shown committing an overtly evil act, even after he discovers Alicia's role as a spy. He and his iron maiden of a mother begin to slowly poison her, but it's the old lady who actually does the deed. Sebastian is shown as a decent guy who just happens to be working with his fellow Nazis. He also seems to truly love Alicia -- they previously had a fling years ago, which was what helped make Alicia the perfect mole.
It's interesting to think what it would be like to remake this movie from the perspective of the Claude Rains character, with an overbearing mother and a mysterious stranger who keeps showing up in an attempt to steal your wife away.
Leopoldine Konstantin plays Sebastian's mother, in a memorable performance. Since Sebastian is seen as such a nice guy, even something of a wuss, she represents the most villainous figure in the film.
One of my favorite games is spotting mother-son cinematic pairings in which the actors portraying them are actually about the same age. Claude Rains was 57 when this film came out, while Konstantin was but three years older. There's one scene where they're interacting in a close two-shot (i.e., both their heads are visible in the frame) and you can see how smooth and unlined her face is, compared to Rains' elegant but craggy features.