Last year, Film Forum revived Jean-Pierre Melville's brilliant French Resistance thriller Army of Shadows and even the most reserved critics freaked out. Now the theater's back with more: Melville's earlier classic (from 1962) is a slick crime flick about a crooked police informer, played by the sly, understated Jean-Paul Belmondo, who sees an upside to every betrayal. This is a master class in the art of the double-cross—and may be the film-geek event of the season.