Leo Martin (William Hartnell) is a low-level member of a smash-and-grab gang run by shady dance-club owner Loman (Raymond Lovell), who is cajoled into a risky job on a major jewelry store. When the robbery goes wrong, and Martin is caught (and his wrists broken), the hood keeps silent and does his stretch in prison -- all along, he nurses a grudge against Loman and his driver Hatchett (Victor Weske) for running out on him. And that grudge grows to full-blown, murderous vengeance when Loman blows off the newly-released Martin as no use to the gang (as his hands aren't what they used to be). Now Martin plans to get even by squeezing Loman dry of everything he has, starting with his peace-of-mind -- he implicates the club owner in a murder, while planning a seemingly perfect alibi for himself, and also manages to latch on to the ring-leader that Loman is fronting for, "respectable" art dealer Gregory Lang (Herbert Lom). Lang has a knack for tying up loose ends -- including Loman -- and thinks he can handle a low-level spiv like Martin, but he doesn't reckon with the latter's rage, deviousness, or resourcefulness. Martin's planning gets him past all of the obstacles in his way, even -- so it seems -- the plodding efforts of Inspector Rogers (Robert Beatty), still investigating the killing that put Martin's plan into operation.