Plot

A police lieutenant is ordered to stop investigating deadly crime boss Mr. Brown because he hasn't been able to get any hard evidence against him. He goes after Brown's girlfriend, who despises him, for information instead.

Police Lt. Diamond is told to close his surveillance of suspected mob boss Mr. Brown because it's costing the department too much money with no results. Diamond makes one last attempt to uncover evidence against Brown by going to Brown's girlfriend, Susan Lowell.—Norman L Cook <cook@ssdgwy.mdc.com>

Police Lt. Leonard Diamond of the 93 Precinct is obsessed with finding evidence against hoodlum Mr. Brown and unsuccessfully exceeds the budget after four years of investigation with his partner, Detective Sam Hill. Police Capt. Peterson orders him to stop the investigation, saying that his obsession is personal since he has fallen in love with Brown's mistress Susan Lowell. But Susan tries to commit suicide and Diamond convinces his chief to follow one last lead, the name Alicia babbled by Susan in the hospital. The powerful Mr. Brown is mad with Diamond's investigation and sends his gangsters Joe McClure, Fante and Mingo to try to stop Diamond. But the reluctant lieutenant insists in his pursue and the criminals decide to kill him. However, they murder Diamond's lover Rita by mistake. Now Diamond's is out for revenge and he will not stop until Mr. Brown is brought to justice.—Claudio Carvalho, Rio de Janeiro, Brazil

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.—Huggo

Police captain Peterson (Robert Middleton) storms into the office of police Lt. Leonard Diamond (Cornel Wilde), critical of Diamond's spending exorbitant amounts of the city budget and his own personal money in an attempt to arrest a crime boss, Mr. Brown (Richard Conte). Peterson says it is a waste of time trying to find something incriminating to bring Mr. Brown to justice because his crime combo does business without accounting books, and furthermore Peterson says Diamond's actual motivation is Diamond's love for Brown's girlfriend Susan Lowell (Jean Wallace). Susan is attended to at all times by Brown's thugs Mingo (Earl Holliman) and Fante (Lee Van Cleef). Seemingly drawn to Brown through his ability to inflict pain, she seems kidnapped and yet willingly waits for Brown's brutal attentions. Attempting suicide, she overdoses on pills, and utters the name "Alicia" as Diamond attends to her in the hospital. Believing this may be Brown's wife, Diamond follows up on this new lead, but Brown captures and tortures Diamond and delivers him back to his boss Peterson, attempting to make Diamond appear drunk. Meanwhile, Joe McClure (Brian Donlevy), a deaf underling of Brown's, tries to overthrow him by enlisting Mingo and Fante to kill him, but they in turn stick with Mr. Brown and kill McClure instead. Diamond makes more headway by locating a former girlfriend of Brown's and Bettini (Ted De Corsia), the former First Mate of Brown's boat. When Brown tries to further kill off his hired thugs and escape, Diamond confronts him again, with new evidence to arrest him.