Perhaps Billy Wilder's masterpiece: though there are at least a half-dozen more offering strong competition, the combination of mordant, cynical observation and tremendous heart makes this one just about unique.
The superbly witty (and wise) script is played to perfection by Jack Lemmon and Shirley MacLaine, and without ever losing sight of its primary purpose as comedy grips audiences as firmly as any drama, from the wry voiceover opening to perhaps the best of those all-time great movie endings on which Wilder so prided himself. Hats must be tipped, also, to the beautiful black and white photography of Arthur La Shelle (though essentially a literary film there are still some great visual touches: the opening scenes, reminiscent of The Crowd, of Lemmon's inhumanly mechanical office existence, for instance, or the amazing romantic shot of Maclaine running through the nocturnal streets at the climax).
And points, especially, for having Fred MacMurray play the reptilian Mr Sheldrake: no other director saw beyond his lovable goofy exterior to show us what he might really be capable of. In Double Indemnity we caught a glimpse here and there of the traditional MacMurray, made mercenary by temptation, but Sheldrake is beyond redemption: the embodiment of the mechanistic, inhumane world in which Lemmon's junior executive C.C. Baxter and MacLaine's kooky lift operator Miss Kubelik are stranded, to both of them a malignant Faust who almost succeeds in distracting them from the realisation that their only hope of salvation is each other. Baxter is the kind of role Fred himself might have played in the thirties; it brilliantly underlines the point that Sheldrake is what Baxter might so easily turn into. But he doesn't, thanks to the radiant Miss Kubelik and Wilder's unwavering belief in the redemptive power of empathy and compromise.