The Third Man (1949)
Director: Carol Reed
Orson Welles (as Harry Lime)
Joseph Cotton (as Holly Martins)
Alida Valli (as Anna Schmidt)
Post-war Vienna: Author Martins learns that his old friend Harry Lime is dead. He isn't. In fact, Lime has become a black-market racketeer who has made a fortune stealing and diluting penicillin, with tragic consequences. When Martins and Lime meet (on Vienna's famous Ferris wheel), Lime offers his, well, philosophy. Welles' Lime embodies evil and charm.
This is a great movie. The cinematography and music alone make the movie worth seeing, over and over.
To see what I mean, check out the film's famous final scene:
To you young people out there: Be thou not a knucklehead. See what you've been missing!