The Big Combo (1955)

At great expense to the police department and thus much to the consternation of Captain Peterson, Lieutenant Leonard Diamond has solely worked on one case for six months: to bring down "Mr. Brown", the head of an organization called the Combination, which is the largest dealer in the illegal movement of money. Brown took over the Combination when its former head, Grazzi, left the country. Peterson and Diamond both know that Brown keeps no official books and is hyper-vigilant about not leaving a trail of any kind that could lead back to him, hence the reason Diamond has no concrete evidence that could put Brown away. Diamond believes Brown's one weak point may be his girlfriend, Susan Lowell, who Diamond has had constantly followed and with who Peterson believes Diamond is in love from afar, making this case personal for him in not liking to think of her in Brown's arms. That latter information would probably not sit well with Rita, a burlesque dancer who is in love with Diamond herself and who Diamond, in taking her for granted, turns to only in his times of need. Two items that Diamond discovers may bring him into Brown's crosshairs: that there is another woman, identity unknown, in Brown's life, who Diamond only knows is named Alicia; and that Susan is in a fragile mental state, probably due to her association with Brown. In wanting to put Diamond away for good, Brown may start leaving those trails he is so careful about hiding. Complicating matters is Mr. Brown's associate, hard of hearing Joe McClure, who felt he should have been in charge after Grazzi's departure, and who may try to use Brown's vendetta against Diamond against him.