The ending is terrific: best car chase done with rear projection ever and a very effective assassination scene. Eli Wallack is a pleasure to watch (as always), but the dialogues are just boring and the characters are plain as hell. That's the problem with most of the "investigation movies" Hollywood produced in the forties and fifties: they're talky and boring and, in the end, not that much cinematic.
An extremely brisk beginning, a pair of villains that will haunt you for days, Richard Jaeckel as the alcoholic wheelman, social etiquette taught by a gay Pygmalion to a psychopathic hit man. 86 minutes of sheer pleasure. Masterpiece.