Mickey is a stable boy for Lady Q, a race horse that has the potential to be a champion. When drunken bum Tom Terry brusquely moves into the stable with him, they are constantly at odds. Because Lady Q loses a big race, her owner plans to sell her to the glue factory, but Mickey buys her with his meager savings. Mickey learns from Tom that Lady Q has a tumor on her foot, and discovers that the derelict was once a brilliant veterinarian. Mickey convinces Tom to operate on Lady Q, and despite his alcoholic shakes, the operation is succcessful. The two take the horse on the road, and soon become very close. Because Mickey is an orphan, he suggests that they "legally" adopt each other. Tom is reluctant, but soon agrees and the two plan to enter Lady Q in a big race. To make money for the entrance fee, they stay at a farm owned by five-time widow Beulah Flanders. When they have almost earned the entrance fee, Tom, who is now a sober and devoted father, tells Mickey to go to the track to get an application blank. While there, Mickey runs into detective Barney Donovan, who reveals that Tom is wanted for his part in the death of a horse and jockey in a fixed race. When Mickey returns to the farm, he pretends that he doesn't care for Tom anymore, strikes him, and leaves with the horse. The next day he is able to get the money he needs by impressing Mrs. Shepherd, a stable owner. Lady Q develops a sore hoof, though, and is only saved by Tom, who arrives with a special shoe for her. Mickey finally confesses that it was his fear for Tom that made him act as if he didn't care, and the two realize that they are truly father and son. Tom is supposed to leave right away to avoid capture, but instead watches Mickey win the race. Although he now has enough money to become a veterinarian, like his father, Mickey is heartbroken when Donovan apprehends Tom. The two have an emotional farewell, but Mickey is relieved when Mrs. Shepherd tells him that Tom will serve no more than a year in jail.