Solly Pitts, the honest hiring boss for the New York City longshoremen, is brutally shot on his stairwell by racketeering union boss Eddie “Cockeye” Cook and his thugs, Tilly Moore and Leo Shaker. District Attorney Howard Rysdale reluctantly assigns the case to inexperienced assistant William Keating, warning him that the wharf has a long and complex history. Solly is alive but weak, and police lieutenant Anthony Vosnick brings Bill to the hospital to question him. There, Solly’s wife Madge, who trusts Vosnick, admits that her husband named his attackers, but Solly, hoping to protect Madge, refuses to speak to the authorities. Vosnick explains to Bill that Solly runs the only lawful area of the pier, and that Cockeye’s superior, Al Dahlke, plans to run him out of town. After failing to get any more information out of Madge, Bill heads to the docks, where the men refuse to talk to him. After drunken longshoreman Midget rails loudly against the racket, Bill watches helplessly as Dahlke sets his henchmen after him. Bill follows Midget to his home, where the broken man, who assumes Bill is on Dahlke’s payroll, bitterly asks him where the police were when the racketeers moved in. Later at the police station, Vosnick explains that Midget once spoke out against the crooks, but after they broke his back, he lost his job and later his wife and children. Although Cockeye presents his falsified alibi for the day of the attack, Bill holds him in jail, but realizes that Solly and Madge’s testimony represent his only hope for an indictment. While looking at an apartment with his fiancée, Dee Pauly, Bill recalls his coal miner father taking him to a union meeting and keeping order with his fists, and Dee counsels him to use his head rather than his brawn. They are interrupted by ex-policeman Sid Wallace, now a private investigator, who invites them to dinner in Chinatown. At the restaurant, Sid introduces Dahlke as “a friend,” after which Dahlke offers his underworld connections to Bill in exchange for letting Cockeye go free. Bill spurns him, prompting Dahlke to make vague threats. Bill goes to Rysdale to push for quick action, knowing that the longshoremen will support the law once they believe it is on their side, but the district attorney cautions him to move slowly and remember that everyone has an angle. The next day, a prisoner named “Monk” Mohler claims that Cockeye offered him money to provide a false alibi. Bill is excited by the breakthrough until Rysdale reveals that Monk merely wants to trade this information for a lightened sentence, and is not a credible witness. With only hours left before he must release Cockeye for lack of evidence, Solly decides to testify against Cockeye, and Bill goes to the hospital to record the dying man’s statement. The police bring Cockeye there for Solly to identify, but Cockeye attacks the ill man, who later regrets that he is dying “a rat.” While Cockeye hires expert attorney John Jacob Masters, Bill and Rysdale review the case, which relies exclusively on Solly and Madge’s testimony. Bill and Rysdale then go to Madge’s apartment and there badger her to test the strength of her conviction, and although she holds up under the pressure, she later receives phone threats that unsettle her. Soon after, Bill and Dee are married, and one of the telegrams they receive at the reception includes another death threat. That night, the hospital calls Madge to inform her that Solly is dying, but she is so afraid to answer the phone that she misses the call. At Solly’s wake, his best friend, Benjy Karp, confesses to Bill that he saw Moore running from Solly’s apartment building the day of the shooting. Bill attends a meeting of the district attorney office, and when the group votes to postpone the trial until they have more evidence, Bill heatedly accuses Rysdale of possible collusion, and insists they take the matter to the mayor. The mayor roundly chastises Bill, who storms out of the meeting. Bill is telling the story to Dee that night when Rysdale informs him that the mayor agreed with Bill’s assessment of the case, and wants Bill to prosecute it himself. At the trial, Masters impugns each witness, painting Benjy as a liar and Solly as uncredible, causing Benjy to lose the little faith he had gained in the legal system. When Bill calls Madge to the stand, she cannot be found. Three days later, Bill finds Benjy at the wharf preparing for an illegal strike against Dahlke. Although Benjy will not back down, he reveals that Madge is in Brooklyn, and Bill convinces her to return to the city under his care. Back at the trial, Masters attacks Madge’s character, then points out that Bill held Cockeye under false pretenses, and finally accuses Vosnick of setting up Cockeye. In their closing arguments, Masters presses the issue of reasonable doubt, while Bill emphasizes the facts in the case and the courage of the witnesses. The jury remains in deliberation for hours, during which Bill learns that Benjy’s men have begun their strike. He rushes to the pier, where Dahlke has arrived with trucks full of thugs, and when Bill punches Dahlke, a riot breaks out. When the police arrive and arrest the group, Vosnick and Rysdale pull Bill out of the melee and into the waiting arms of Dee. Midget staggers out of the crowd into the liquor store, where he hears a radio announcement that Cockeye, Moore and Shaker have been convicted, in one of the first victories of its kind in the city waterfront. Tottering into the street in delight, Midget finds Bill’s abandoned briefcase, and picks it up reverently.