At the racetrack, a jockey is thrown from a dangerous, temperamental horse called Maneater. Exasperated, the owner of the horse, Sir Charles Bailey, dismisses his trainer, Bannerman. At the suggestion of his daughter, Monica, he instates her boyfriend, Jimmy Armstrong, to train the horse for the upcoming Bargrave Stakes. Bannerman is furious.
Soon afterwards, a pickpocket steals Sir Charles's wallet. George, an ice cream seller at the racetrack, is wrongly suspected of the crime. Sir Charles calls a policeman and chases George, who escapes on a train. Armstrong and Maneater are also on board, travelling to Armstrong's stables. Seeking refuge on the journey, George accidentally falls through a ventilator into Maneater's horsebox.
At the end of the journey, Armstrong opens the horsebox to find George asleep with Maneater. Armstrong realises that Maneater likes George because he is not scared of him: he does not know of the horse's reputation as a savage animal. Armstrong enlists George to ride the horse to the stable and hires George to look after the horse. He warns his employees that George must not find out the truth about the horse. Sir Charles, at the house next to the stables, spots George and, thinking that he is a criminal, locks him in a cupboard and telephones the local policeman, the aged Sergeant Johnson. Monica, aware that George is innocent, frees him. Disguised as a housemaid, George escapes from the house, and goes to a nearby village to find lodgings. Squib, a small boy, offers him a room at his Grandfather's house. Unknown to George, Squib's grandfather is Sergeant Johnson, and the spare room is a cell at the local police station. Ann, the policeman's pretty daughter, convinces him to rent the room.
The next day, Bannerman, now training a rival horse for the Bargrave Stakes, watches Maneater performing impressively under George's training. Meanwhile, Armstrong enlists George as Maneater's jockey for the race.
George, falling in love with Ann, takes her to the local fair. Meanwhile, Bannerman attempts to blackmail Sergeant Johnson, who is unofficially letting out the police cell, into convincing George to work leave Armstrong's employ. Having bet all his savings on Maneater in the forthcoming race, Johnson refuses to give in to Bannerman's demands. At the fairground, George is once more recognised and chased by Sir Charles, but evades capture again.
Bannerman instructs his henchmen to stop George from riding in the race. Squib reveals to George that the horse he is to ride is Maneater. George is scared, and loses Maneater's confidence. Armstrong takes George to Dr. McGregor, a nerve and brain specialist, so that he can learn to conquer his fear. As a result of McGregor's cranium manipulation treatment, pressure is removed from George's nerves, and he is filled with self-confidence. The doctor warns that if George is hit on the head, his fears will return.
Armstrong rushes George to the stables, but before the race a horseshoe hits George on the head, undoing his brain treatment. He is again too scared to ride Maneater. Armstrong forces George into a van with Maneater, and they are driven off to the racetrack while Armstrong goes in search of the doctor. George escapes from the van en route. George sneaks back to his lodgings, where Ann tells him that it would be safest if he took a train to London to avoid the race. Squib, however, follows George as he leaves and tells him that Ann is in love with him. Inspired by Ann's devotion, George decides to ride Maneater in the race and heads for the racetrack. Bannerman's henchmen kidnap George, but George overcomes them and after a hair-raising car journey, arrives at the course in time to ride in the race.
Overcoming various obstacles, George and Maneater win the race. Afterwards, Maneater, lurching forward, throws George from the saddle on to the top of a horsebox, where Ann sits waving. George and Ann fall through the roof of the horsebox. Sitting in the straw, they kiss. Maneater, poking his head through a curtain behind them, snorts his approval.
