A taxi driver gets mixed up with jewel thieves.

New York City taxicab driver Ernie Driscoll watches the television program "Great Fights of Yesterday," which is replaying the world heavyweight boxing match that ended his boxing career. Although he dreams of opening his own gas station, Ernie's wife Pauline berates him for living in the past and blames him for failing to provide adequately for her. After Ernie drops Pauline off at the florist shop where she works, he seeks advice from his best friend, dispatcher Stan Hogan, who good-heartedly suggests that Ernie whisper in Pauline's ear that they should start a family. Aspiring actress Linda James joins the men at a drugstore lunch counter and shares the good news about her upcoming audition for a Broadway play. At the florist shop, meanwhile, Pauline plans to run away to Paris that night with her lover, thief Victor Rawlins, after he closes a $50,000 deal. Ernie drives up to the shop hoping to smooth things over with Pauline, and sees her kissing Victor. When Victor attempts to hire Ernie's cab, unaware that the driver is Pauline's husband, Ernie angrily drives away. Pauline is terrified because Ernie has seen them together, and tells Victor that she fears for her life. Victor brings Pauline to a pet shop, where he meets with Christopher, who hired him to steal some diamonds. Christopher, who distrusts women, now refuses to pay because Victor murdered the diamonds' owner and has involved Pauline in the deal. Pauline was unaware of the murder and grows angry when she hears about it, but Christopher's thug Mickey slaps her and draws his gun. At the cab company, Stan attempts to curb Ernie's explosive outburst about his wife's betrayal, even after Ernie unintentionally slams him against a car. Ernie agrees to finish his shift, but is waylaid by Linda, who says she killed the play's producer when he tried to force himself on her. Linda takes Ernie to the apparently empty theater to see the body, and after she dramatizes the event, Ernie reluctantly agrees to dump the body in the river. To his horror, the "body" gets up, after which several people, including the play's director, Waldo Daggett, the writer, Lloyd Morgan, and the publicist, appear from the dark house to congratulate Linda on her performance. Ernie then learns that Lloyd arranged the ruse to prove Linda's acting ability to Daggett. Linda gets the part but loses her friend Ernie, who is so infuriated by the practical joke that he strikes Morgan when the playwright attempts to pay him off. Several other men get involved in the fray, but Ernie overcomes them and leaves. The publicist then calls the police in hopes that even negative publicity will help the play. Ernie seeks solace at his former gymnasium, where he asks manager Pop Durkee to get him back into the ring. Pop gently refuses because the eye injury that ended Ernie's boxing career could cost him his sight if he is hit again. In another part of town, Pauline accompanies Victor to his apartment, where he convinces her to call Ernie and arrange for him to meet her at a nearby bar. After she hangs up, Victor wraps a scarf around Pauline's neck, in an apparent loving gesture, but continues to pull it tight until it strangles her. When Pauline fails to show at the bar, Ernie returns to their apartment and packs his belongings. Linda arrives soon after to apologize. After assuring him she has quit the play, she warns Ernie that there is a warrant for his arrest for assault and battery. Although Ernie is still angry at Linda, she refuses to leave his side and when they climb into his cab, they discover Pauline's dead body in the back seat. Ernie immediately suspects Victor, and although he does not know his name, he remembers the address Victor gave when he mistakenly approached the cab at the florist shop. Ernie finds Victor's apartment and breaks in, but is surprised by the arrival of Mickey, who strikes him, demanding information about his knowledge of the diamond heist. Ernie turns the tables on Mickey and brutally beats the thug into revealing all the details about the robbery and his wife's plan to leave him. Linda, who has been waiting outside near the car, enters the apartment just after Ernie beats Mickey until he becomes unconscious. Linda warns Ernie that the police have found his car with Pauline's body inside. At the pet shop, Victor forces Christopher to pay him the money he owes, then tells him that he has rid himself of Pauline and framed her husband for her murder. Ernie takes Linda to the cab company, where Stan asserts his loyalty to Ernie. Based on Mickey's information that Victor and Pauline were planning to board a freighter in Jersey City, Stan contacts other local cab companies to ask if they have driven any fares there. When they are alone, Linda reassures a bitterly disillusioned Ernie that she is devoted to him. While they are waiting for information, a forger named Monk informs Christopher that he will be meeting Victor at a port-side café at 99 River Street in Jersey City to give him a falsified passport. Ernie and Linda drive to the same address after obtaining the information from Stan, but a policeman orders Ernie to move his cab away from a hydrant, so Linda goes into the café alone. Linda pretends to be drunk, but overhears Monk asking the bartender for Victor. After Monk leaves, Linda attempts to seduce Victor and draw him out of the café where, unknown to her, Mickey is forcing Ernie into a car with Christopher and his other thug, Bud. When Linda's attempt at seduction fails, she lures Victor by mentioning Pauline's name. Victor then forces Linda into the alley and slaps her, but is interrupted by Mickey, who marches them both at gunpoint down to the docks. Bud follows closely in Christopher's car until Ernie, who had been knocked unconscious, revives and strikes Bud. Ernie jumps to safety before the car crashes into a massive crane, then locates Linda, who has escaped from her captors. While Linda goes for the police, Victor knocks out Mickey and shoots Ernie in the chest. Although wounded, Ernie musters the willpower he learned as a boxer to pursue the gunman until Linda arrives with the police. One year later at the gymnasium, Ernie tells Pop that he and Linda are partners in marriage and business, as he has opened a gasoline station. Stan repeats his marriage advice, so Ernie whispers a suggestion to start a family in Linda's ear and she responds with a delighted smile.