Newspaper editor Jim T. Austin and his wife Marge race into a Midwestern police station to escape the gangsters following them, and beg the sergeant to help them reach the capital safely. When the sergeant cannot hail the captain, Jim begins to record his story on a police tape machine: Weeks earlier, in a nearby mid-sized town, Jim is contacted by investigator Clyde Nelson, who insists they meet in secret at the local library. There, Nelson reveals that when he investigated an alimony suit brought by Margaret Sirak against her ex-husband, insurance magnate Murray Sirak, he uncovered what appeared to be a massive gambling ring run by Sirak and involving police chief Gillette. The police then began a campaign of threats against Nelson, from issuing traffic tickets to tapping his phones to following him. Recently, his investigator's license has been revoked, and Nelson, who fears for his life, urges Jim to break the story of police corruption in his newspaper. Jim is doubtful, but when he sees policemen outside the library, his curiosity is piqued. He visits Gillette, who assures him that Nelson is unstable and that they have been tailing him only to make sure he does not spread any more rumors. Jim is reassured until a few weeks later when he gets an urgent call from the investigator, who begs Jim to meet him. Jim refuses, but when he later hears that Nelson has been killed in a hit-and-run accident, he races to the morgue. There, Mrs. Nelson tells him that a car with Florida license plates had been following them for days, and blames Sirak for her husband's death. Over the next days, Jim runs a series of editorials questioning why the police are not investigating Nelson's death more thoroughly. When Gillette chastises him, Jim responds that he will look into the death himself, and visits laundress Margaret. She refuses to answer his questions, so he searches Nelson's office and discovers a note written by Margaret listing all the bookies in the area. Although he receives no information from the bookies he contacts, he begins to notice a police cruiser following him. Jim then visits the warehouse of the last bookie on the list and finds a familiar-looking man running a business in the back. Looking through press clippings, Jim realizes that the man is actually powerful mob gangster Dominick Fabretti. Jim stations young reporter Phil Harding at the warehouse to report on Fabretti's actions, and when Phil finally sees the gangster come out, he contacts Jim. The two take a photograph of Fabretti, and after the eager reporter develops it that evening, he is savagely beaten by gangsters, who also steal the film. Later, Sirak visits Jim at his office and offers him a bribe to stop investigating. Jim's partner, Don Carey, hears Jim turn Sirak down and urges him not to try to reform the world. Soon, Jim notices a car with a Florida license plate parked outside his house, and realizes his phone has been tapped. In addition, the paper's advertisers, many of them bookies on the side, cancel their ads and threaten to retaliate. At home, just as Marge tells Jim that she cannot continue to live in fear, Margaret appears. She sobs drunkenly that her ex-husband was forced to go into business with mobsters, and when Nelson found out, the gang had him killed. She agrees to Jim's request to sign a deposition, but the next day, she does not show up at the lawyer's office, and Jim finds her dead in her apartment. The police rule her death a suicide, and although Jim writes a scathing editorial against them, Don refuses to print it because there is no proof of murder. Quitting in anger, Jim confronts Gillette, who accompanies him to the warehouse. They find it already cleaned out, however, and the police chief tells Jim that they are powerless to stop mobster involvement in bookmaking. Jim then turns to Reverend Nash and the other local ministers. Although they are alarmed at the extent of the problem, they decide that the corruption is too widespread to stop. That night, Jim is sitting in his darkened office drinking dejectedly when he sees a memo from Senator Estes Kefauver about the Special State Committee to Investigate Organized Crime in Interstate Commerce, and realizes that he must get to the committee in the capital at once. Although Sirak shows up and offers one last opportunity to take money in return for stopping his search, Jim refuses, and he and Marge leave at midnight for the capital. On the way, however, they see the Florida car trailing them and are forced to flee to the nearest police station. There, Jim finishes his story just as policemen arrive to escort him to the capital. Although a threatening note is slipped to him as he is in the doorway of the committee, Jim bravely enters the room.