The story picks up in 1880s England, when widower Squire Wendon's (Charles Evans) mare Duchess is about to give birth to a foal. He has denied his adolescent daughter Anne (Mona Freeman) to watch, but the girl sneaks into the stables and watches anyway.
Roy Rogers, a horse dealer and a peddler of leather goods, is hoping to mate his mare named "Lady" with Golden Sovereign, a stallion owned by rancher Gabby Kendrick (George "Gabby" Hayes). Kendrick refuses, preferring to mate the stallion with his own stock. Brett Scoville (Jack Holt), a wealthy rancher and nightclub owner, wants to mate the stallion with his mare, as well, and to that end, steals the stallion. Golden Sovereign breaks free, finds Lady, and has a romantic interlude with her in the hills.
The film is a silent character sketch that shows Chimmie Hicks (Charles E. Grapewin) imitating a man at the races winning and losing. Filmed on a bare stage with a dark backdrop, the sketch captures Chimmie in a three-piece suit and overcoat holding a racing program while watching a race taking place offstage. It shows him excitedly jumping and pantomiming that his horse has won the race. A second man enters the frame and gives Chimmie his winnings. Chimmie returns a sum of money to the booker to place another bet. The next race begins and Chimmie again shows great excitement, which quickly turns to despair and anger as the horse loses. The bookie returns, collects all of Chimmie's money and his watch. The gambler falls to his knees, shakes his arms toward the sky, and tears up his racing form, scattering the pieces on the ground. He rises and sadly begins to leave the stage.
As summarized in a film publication, a human love story was added to the horse story, which includes a fox hunt and race. At a house party given by Squire Gordon (Steppling), his daughter Jessie (Paige) and Harry Blomefield (Morrison) are playing games with the children, although they have reached the age where Harry realizes that he loves her. Among the guests is Jack Beckett (Webb), who lives by his wits and has gained entree as a favorite of the haughty Lady Wynsaring (Farrington). Squire Gordon gives Lord Wynwaring (Peacocke) 800 pounds for his wife's charity, which Jack steals from the Wynwaring room. During a fox hunt the next morning, Jessie's brother George (Kenny) is killed in a fall from his horse. Jack puts the stolen money in the pocket of the dead man and tells Jessie that her brother was a thief. To prevent him from telling her mother, Jessie agrees to marry Jack when she comes of age. Jessie meanwhile realizes that she loves Harry, who cannot understand her wish to marry Jack. Several years pass and Harry tries to elope with Jessie, but is foiled. After a race sequence, Black Beauty carries Harry to victory and to Jessie, foiling the plans of the villain Jack.
Al Jolson plays Gus, a loyal stable boy and jockey to a rich family in the South that has been interested in horse racing and breeding horses for generations. (In a flashback we see Jolson's grandfather, who also worked for the same family back in 1870.) The young heir of the family, Jack, loses a lot of money by gambling and is blackmailed by the crooks he lost to for forging a check. They convince Jack to ask his mother to replace Gus with another jockey for the family's racehorse, "Big Boy", but she refuses. The crooks frame Gus and he is discharged for tampering with the horse. Gus is replaced by a jockey who has been bought off to lose on purpose. Gus find works as a waiter in a fancy restaurant. While working there he uncovers the details about the race throwing plot and he reveals this to Hughes and then, with his help, outsmarts the crooks just in time to then ride "Big Boy" to victory.
Joel Curtis (Ted Donaldson) is a young orphan who is living with his grandmother, Aggie Curtis (Jane Darwell), on her ranch. Joel finds an orphaned colt in the nearby woods, and names the horse Red. Joel learns that Grandma Curtis has extensive debts, and will be forced to sell her ranch to pay them off. Joel is friends with Andy McBride (Robert Paige), a ranch hand at the nearby Moresby Farms. Joel convinces Andy to help him train Red as a racehorse, with the intention of selling his beloved horse to pay off his grandmother's debts.
Terry is a teenaged girl whose Uncle Willy, a horse trainer, dreams of winning the Derby. He bets everything on his horse Sunset, then collapses and dies after it loses.
Joe is paralyzed by a wild horse, a strawberry roan. His father, Walt, tries to kill the horse in anger but is unsuccessful and the horse escapes. Autry, who stopped Walt from killing the animal, is asked to leave the ranch. He finds the horse and trains it in the hopes of returning it to Joe to give him the will to overcome his disability.
Hugo Z. Hackenbush (Groucho Marx) is a veterinarian who is hired as chief of staff for the Standish Sanitarium, owned by Judy Standish (Maureen O'Sullivan), at the insistence of her most important patient, the rich Mrs. Upjohn, (Margaret Dumont), who insists on being treated only by Dr. Hackenbush. The Sanitarium has fallen on hard times, and banker J.D. Morgan (Douglas Dumbrille) is attempting to gain control of it. Judy hopes that Mrs. Upjohn will make a large donation and stop that from happening.
Horse racing enthusiast T.H. "Randy" Randall is a happily divorced man nowadays. On the day of the one-year anniversary of the divorce, he and his former wife, Valerie, go to the restaurant where they first fell in love. Randy was responsible for breaking up their marriage in the first place, by spending more time with his race horse than Valerie. At the restaurant, while they are dancing, the police come and arrest Randy for not paying his alimony to Valerie. He is thrown in jail, and desperate to get out he starts to plan how to get rid of his obligation to pay alimony altogether. He finds that the best solution is to get Valerie to marry someone else, and so he tries to fix her up with a friend of his, Paul Hunter. They both accompany Randy to a party at the estate of a rich eccentric socialité, Ethel Hilary, who has a special interest in collecting original characters to her circle of friends at the estate. Besides Randy and his company and yoga master Dickie Brown, a very handsome man named Freddie arrives to the estate. He is unknown to everyone, but is soon romantically interested in Valerie, trying to get her interested in him by singing her a serenade in the night. She mistakes the singer for Randy, and he discovers that Valerie is more interested in Freddie than Paul, and forces her to go with him instead of Freddie to a picnic. Problems arise when Randy gets a flat tire and Valerie has to be escorted by Freddie anyway. She manages to get Freddie to propose to her at the picnic, but is devastated to learn that Freddie is already married. Having re-discovered his interest in Valerie, Randy gets jealous of Freddie, and wants to remarry his ex-wife. Randy quickly proposes to Valerie and she immediately accepts, having longed a long time for him to utter those words. Unfortunately Randy's lawyer, Bill Carter, accidentally reveals that Randy has had a "plan" to get rid of the alimony, and Valerie gets second thoughts about marrying him again. She decides on marrying the dull Paul instead, upset with Randy's presumptious behavior. The marriage is about to take place at the estate, but on the wedding day both Randy and Paul turn up as grooms. During the ceremony, Randy's own race horse Ajax participates in a race broadcast over the radio. The ceremony is quite disturbed by the race, and just when Valerie has decided to marry Randy, the horse wins the race to both their joy.
The Stooges are conmen who are selling phony racing forms to everyone especially they sold one to a man which he said that the racing form was expired and the stooges stole his money and threatens to call the cops. After evading the policeman they help a destitute mother and her daughter by utilizing the money from the child's piggy bank, and ultimately winning a horse race. Riding high on their win, the boys come across two swindlers who trick them into buying retired race horse, Seabasket (a play on Seabiscuit). Broke again, the Stooges start taking care of the old horse, with Curly managing to accidentally swallow a Vitamin Z pill meant for the horse. However, the error allows Curly to give birth to a colt, which they crown as another winning race horse.
Sorrowful Jones is a New York bookie who keeps his operation hidden behind a trap door in a Broadway barber shop. He suffers from a financial setback when a horse named Dreamy Joe, owned by gangster Big Steve Holloway, unexpectedly wins a race. Jones has to pay all the many customers betting on the horse to win, which empties his pockets completely.