As fishmarket owner William Sheffield is robbed and murdered outside his New York City home, Swedish seaman Sven Norson observes the crime from across the street. The police soon find the getaway car and fingerprints of ex-con Frankie Korvac, a Sheffield employee who names co-worker Johnny O'Hara as his accomplice and the triggerman. When plainclothes detective Vince Ricks goes to arrest Johnny, he runs away, fearful that Ricks is a henchman for gangster Knuckles Lanzetta, the older husband of the woman with whom Johnny is having an affair. Johnny's parents call former criminal law attorney James P. Curtayne, hoping that he will defend their son, whom Jim had gotten out of trouble as a youth. At first recovering alcoholic Jim refuses the case, in deference to his protective daughter Ginny, but soon acquiesces. Johnny will not tell Jim that he was with Mrs. Lanzetta when the murder took place and will not explain why he has been keeping a gun. Although the case seems weak, ambitious District Attorney Louis Barra is convinced that he will win because Johnny recently argued with Sheffield, and Frankie swears that Johnny planned to kill their boss for a gold bar he kept in a suitcase that was found in Johnny's car. While Ginny tells her long-time boyfriend, Jeff Chapman, that she cannot marry him because her father needs her, Jim goes to see Knuckles. Knuckles has no idea who the murderer is, but tells Jim that the day before he died, Sheffield had bragged that he would soon repay a $20,000 loan. At the start of the trial, Jim is in top form, but when he repeatedly fails to break Frankie's testimony, Jim is despondent and has a bitter argument with Ginny after starting to take a drink. One afternoon, Ricks, who is an old friend of Jim, tells him that there is a secret eyewitness who has approached Barra. After Ricks leaves the bar, Jim orders a drink and is approached by Norson, who implies that he might be willing to change his story for money. Though initially repelled, Jim follows Norson to a table, writes him a check for $500, then gets drunk. When Norson takes the witness stand the next day, Jim is shocked that he is sticking with his orginal story, then sees the $500 check in Barra's hand. O'Hara is convicted, after which Barra berates Jim but does not immediately file bribery charges. A few days later, at the funeral of a mutual friend, Ricks tells Jim that an attractive woman claiming to be Johnny's sister had attempted to visit him. Suspicious, Jim asks Johnny's parents to look through his things and finds an Italian-English dictionary and a receipt for a postal box. The postal clerk will not let Jim get Johnny's mail without a key, but Jim looks through the window of the box and sees a letter addressed in a woman's handwriting. Suspicious that the woman could be Knuckles' attractive young wife, Jim confronts her. Although frightened that her husband will learn of her affair, she tells Jim, then Barra and Ricks, that she was with Johnny the night of the murder. Barra believes her, but her statement would not hold up in court as Johnny protectively refuses to corroborate her story. Under further questioning, she reveals that Knuckles was very interested in Johnny's trial and once made a comment to a cohort implying that the suitcase was hiding something "right under our eyes." On a hunch, Barra has the suitcase taken to the narcotics unit, where agents find $200,000 worth of dope hidden in the lining. Now working with both Barra and Ricks's help, Jim goes to Knuckles and says that he needs to call in a long-owed favor. Knuckles reveals that he did learn who killed Sheffield and agrees to help in exchange for the suitcase, which Jim says has just been released to him. Jim goes to the meeting place, Sheffield's house, wearing a police wire, with Barra and Ricks nearby. When the wire does not work properly inside the house, Jim realizes that he is in grave danger and calls Ginny, who is decorating their Christmas tree. He is casual with her, then asks to speak with Jeff, and sternly tells him to marry and take care of Ginny. A moment later, James Korvac, Frankie's older brother, who is a large man like Johnny, approaches the house. Korvac reveals that he has killed Knuckles, then takes Jim for a walk at gunpoint. Although plainclothes narcotics officer Betty Clark tries to distract Korvac, a shootout ensues when Frankie's brother Angelo drives up in a getaway van. Jim is mortally wounded before the police can move in and capture the brothers. Barra tells Ricks that he will not file bribery charges, but learns that it is too late to tell Jim.