At a big city racetrack, bookkeeper Marvin Unger covertly gives bartender Mike O’Reilly a note detailing the time and place of a meeting later that night, then retrieves his small winnings from cashier George Peatty. A little earlier that same day, patrolman Randy Kennan meets with loan shark Leo and assures him that he will be able to repay his entire loan within two weeks. At Unger’s apartment that evening, ex-convict Johnny Clay, just released from prison after serving a five-year sentence for robbery, reunites with his girl friend Fay and promises her that his detailed plan for an upcoming heist will guarantee their future together. A little later, George arrives at his apartment where his beautiful but cynical wife Sherry nags him about their constant poverty. In anger, George reveals he may be coming into a large amount of money, then refuses to explain, prompting Sherry to complain that George does not trust her. After George departs for a meeting, Sherry meets her lover, Val Cannon, and confides that George finally confessed to being involved with a small gang of men who plan to rob the racetrack proceeds. At eight o’clock that evening, Johnny meets with Unger, O’Reilly, Kennan and George to finalize their roles for the robbery. Johnny estimates that the track take will be nearly two million dollars and reveals that two other trustworthy men will assist them. While the men express concern over the two unknown conspirators, Sherry is caught eavesdropping just outside the room. George hastily claims his wife must have suspected him of cheating and followed him. After ordering the men away, Johnny threatens Sherry, telling her that if she interferes in the robbery she will only prevent George from receiving his cut of the proceeds. Later that night at the Peattys’ apartment, George decides to withdraw from the plan, but Sherry convinces him that the money will rejuvenate their troubled marriage. Three days later, Johnny meets with burly, former wrestler Maurice Oboukhoff, who agrees to start a brawl at the racetrack bar just before the critical seventh race when the robbery will occur. The same day, Johnny hires sharpshooter Nikki Arane to shoot racehorse Red Lightning during the seventh race in order to heighten the planned pandemonium. Johnny then rents a motel room from Joe Piano, the father of his prison cellmate, and stores a machine gun there. The next morning, Sherry awakens early to find George already up and surmises this is the day of the planned heist. Before departing for work at the track that morning, O’Reilly bids farewell to his invalid wife and promises he will be able to provide better doctors for her soon. O’Reilly then stops at a bus station locker where he picks up the machine gun in a flower box that Johnny had placed there earlier, then continues on to the track. When Nikki drives onto the track grounds he is diverted by a guard, but convinces the man to let him park near the track. Some miles away, Kennan telephones headquarters to report a radio malfunction in his squad car, then drives on to the track. Just as the seventh race begins, Maurice, feigning drunkenness, starts a fight with O’Reilly at the bar and all of the building guards are summoned to quell the brawl. As planned, halfway into the race, Nikki shoots and kills Red Lightning, whose collapse causes several horses to go down and excites the crowd and track personnel. While trying to flee the parking lot, however, Nikki panics and is shot and killed by a guard. While the guards are busy trying to subdue Maurice, George lets Johnny into the back office. Wearing a disguise, Johnny takes the gun hidden in O’Reilly’s locker and holds up the accountants in the central office. After locking the men away, Johnny places the money, his disguise and the gun in a duffel bag, which he then throws out the window to Kennan, who is waiting below. A little later at a prearranged apartment, Unger, O’Reilly, Kennan and George are waiting for Johnny, who is bringing the money that Kennan has left at the motel, when Val and accomplice Tiny burst into the room and demand the track proceeds. When Val mocks George, revealing that he learned of the job from Sherry, George shoots him. Val squeezes his shotgun trigger before collapsing and the spray kills all of the other men and severely wounds George. Delayed by traffic, Johnny arrives at the apartment fifteen minutes late and sees the bleeding George stumble across the street to his car. Because the men had agreed that if anything went wrong, the one in possession of the money would keep it and divide it with the others at a later date, Johnny drives away with the money. George arrives home and confronts Sherry, who cautions him to leave before Val arrives. George denounces Sherry before shooting her, then dies from his wounds. After placing the bills in a large, old suitcase, Johnny discovers that the locks do not work but proceeds to meet Fay at the airport where he has pre-purchased tickets for a flight to Boston. Although Johnny insists he must be allowed to carry the bulky suitcase on board, the airline officials refuse and he reluctantly checks it. Johnny and Fay then go outside to watch the luggage being loaded onto the plane. Just then a small poodle runs onto the tarmac, forcing the luggage-cart driver to swerve. During the maneuver, Johnny's suitcase falls to the ground and breaks open, releasing all of the bills, which whirl through the air. Fay pulls the stunned Johnny away and they exists the terminal, but an airline official reports Johnny as the suitcase owner to two plainclothes policemen. As Fay desperately tries to hail a cab, the two policemen walk toward her and Johnny.