In Detroit's union hall, during a holiday get-together of members of United Auto Workers Local 2201, a bomb is placed under a pinball machine by hit-man Pete Link, who then flees. The subsequent explosion kills four men, one of whom is the brother of senior union member Blair Vickers. At the hospital, Blair tells police chief Ben Macauley and inspector Max Harkness that he is certain that the blast was ordered by former union boss Gus Linden, currently finishing a five-year prison sentence for corruption. Blair is later appointed by the head of the UAW-AFL to lead an effort to prevent criminal infiltration into the union. At home, Blair is confronted by Linden's daughter Barbara, who accuses him of framing her father. In the state jail, Linden meets with several of his henchmen just before his release and begins plans for running against Blair in the election at Local 2201, which he foresees as a springboard to controlling unions nationwide. As Linden leaves prison, Blair addresses the men of Local 2201 and warns them of Linden's intention to take over the union again. Blair assures the men that they will have police protection and urges them to report any threats or bribes in connection with the upcoming election. Linden is welcomed home by Barbara, his timid wife Ethel and their hostile son Gregg. When Barbara attempts to discuss her visit with Blair, Linden angrily orders her to stay out of his business life. Later, Barbara confronts Gregg about his decision to drop out of college because of his humiliation about their father's incarceration, but Gregg storms out of the house. The night of his homecoming, Linden attends a party, where he reunites with his longtime girl friend, Joni Calvin. Meanwhile, Gregg goes to Blair's apartment with a handgun and blames Blair for framing his father. Max and Blair subdue the young man, and Blair has Max release Gregg into his custody. At the party, Joni is disappointed when Linden rejects her suggestion that they marry and considers turning down his offer to sponsor her own modeling agency. Blair arrives at the party with Max and Gregg, who is stunned to find his father consorting with known criminals. Joni drives Gregg home and encourages his romantic interest. A few days later Linden is frustrated about not being able to have any of his men hired at the 2201's Malick plant, and has hiring boss Jenkins beaten up and his family threatened. Terrified, Jenkins complies and within a few days, several of Linden's men have jobs at Malick. When several union men complain, Jenkins denies he was coerced, but "Preacher" Branislav remains dissatisfied, and reports the hirings to Blair. Blair arrives at Malick and is surprised to find Barbara working there. After Barbara explains that she is looking for proof that he framed her father, she and Blair find Preacher addressing a large group of men about the rapid infiltration of gambling into the union. As Jenkins starts to protest, one of the new men cuts the ropes holding some metal beams, which fall and kill Preacher. Blair and several men chase the man and, as Barbara watches in horror, corner him on a tower where he falls into the path of an oncoming train. Blair grows despondent thinking about the effect that fear will have on the elections. Soon many workers at the plant are in debt to Linden's men, and Barbara observes the developments with mounting confusion. Linden orders Jenkins watched, while Joni continues romancing Gregg, who remains unaware of her connection to his father. Joni asks Gregg to be the partner in her new modeling agency and he accepts, although she advises him not to inform Linden. When Jenkins tries to set up a meeting with Blair and Ben, he is gunned down by Link. Knowing Joni and Gregg will be there, Blair asks Barbara to dinner at a swank roadhouse. Barbara grows increasingly distressed when Blair reveals Joni's identity and shows Barbara police files confirming Gregg's deep involvement in the illegal workings of Joni's agency. Distraught, Barbara flees in her car and crashes several miles away. At the hospital, Blair confronts Gregg, explaining why Barbara was upset and informs him that unless he cooperates with the police, he will be arrested. Gregg agrees and allows the police into the agency, where they discover a list of powerful men involved in illegal dealings. Blair and Max see Joni and inform her that they have evidence against her, and as she was born overseas, could be deported or arrested. After admitting that her partnership with Gregg was intended to get back at Linden for refusing to marry her, Joni agrees to help. Blair visits Barbara in the hospital to explain about Gregg and the impending set-up of Linden and she gives him her blessing. The police then surround Joni's apartment building, and Blair and Max wait on the balcony as Linden arrives with Link, having learned of Gregg's involvement with Joni. Joni has a recording device on, which records Linden's confession about ordering murders. When Link threatens Joni, Max shoots him and is shot in return. After a furious fight, Blair subdues Linden and assures him that the world will hear the taped admittance of his guilt.