Jay Trotter drives a taxi cab. His close friend Looney, also a cab driver, has a secret microphone in his taxi to record his passengers' private conversations. Looney has a new tape of two men talking about an upcoming horse race and how one of the race horses, due to unethical practice by its owner and trainer, "they were holding the horse back", is a sure thing to win big. Jay hears the tape Looney plays, and with Looney goes to the track to place a $50.00 win bet on the horse—despite the fact that the day before Trotter had told his wife Pam that he would quit betting forever and stay home to "start their marriage over" at noon. In the restroom of the bar next door to the racetrack, he prays to God, saying, "Just one big day, that's all I'm asking for, one day, I'm due." A man exiting the bathrooms overhears him, and says "Ya? so's Jesus. Let it ride." Jay promptly places a $50 bet on the horse that he received the tip on from Looney's tape. Looney refuses to bet the tip, instead betting on a horse named, "June Bug"—the same name as a cat Looney once owned. Trotter's horse wins the race in a photo finish and pays $28.40 to win. Armed with a newfound sense of confidence, after cashing his win bet, Jay approaches the two men from Looney's cab ride and generously gives them the tape of their taxi conversation. Out of gratitude, they give Trotter a good tip for the next race. He again places a large win bet, and wins again. Sensing that this could be his "lucky day" Jay intends to "let it ride". Just before the next race, before he can make another bet on a horse suggested by someone else, Trotter is suddenly arrested in a case of mistaken identity. After he is soon released, he realizes the horse he was going to bet has lost. Now, he really feels this is his "lucky day". After being released, Trotter resumes his lucky wagering streak. As he accumulates more money, and uses his new clubhouse friends' membership in the track's exclusive clubhouse dining room, he starts meeting other well-to-do gamblers, including the wealthy Mrs. Davis, and a sexy vixen named Vicki. Trotter soon becomes a hero to the ticket seller, whose window he uses to wager every time, and to the customers of the track's bar. He also hires a track security guard to protect him. However, Trotter has again totally neglected his wife Pam. Pam realizes he must be at the racetrack. She flies into a rage when she confronts him at the track clubhouse. Trotter calms her down a bit-and tells her of his hot streak. He cannot decide on a horse in the next race-so Trotter takes a survey of the track patrons and, eliminating any selection they give him, bets on the remaining horse—Fleet Dreams, which wins. Jay decides to call it a day and goes home to Pam, buying her a diamond necklace on the way. At home he finds Pam intoxicated and passed out. He heads back to the track to help the patrons of Marty's bar across the street, but when he suggests sharing his luck by betting their money together, they all balk at the idea. Disconcerted, Trotter goes for a walk around the track. Vicki suddenly offers to "go to bed with him." Jay "breaks the fourth wall" by saying to the audience, "Am I having a good day or what?" Ultimately, he turns Vicki down by professing his love for his wife. Jay makes a final bet of $68,000 after Looney advises him not to bet on Hot to Trot. As the race begins, Looney and Trotter argue over everything, and the main characters all make resolutions. In Vicki's case, she vows to give up rich guys and consider a poor one, looking at Looney. The race comes down to a photo finish. While everyone awaits the result, Pam shows up to thank Jay for his lovely gift and to tell him not to worry about the money, when the announcer reports the winner: Hot to Trot. The entire racetrack erupts in celebration, and Pam asks, "Why is everyone cheering?" Jay replies, "Because I'm having a very good day."
