Jim "Buck" Turner wins big at the horse races then loses it all playing roulette that evening. Broke, he rents a room at the boardinghouse run by Mrs. Mayhew and her children, George and Marge Mayhew. Although Marge is dating well-to-do Pres Barrow, she falls in love with Jim and agrees to marry him if he gives up gambling and gets a regular job. While working as a night clerk at the Hotel Northland, Jim fights with one of the guests, John Bright, and is fired as a result. Jim angrily confronts Bright, who is amused by his aggressiveness and offers him a job as his representative at the dog races. At the track, he renews his friendship with Valerie Wilson, an old girl friend. To his surprise, he is enchanted by one of the racing dogs, Dark Hazard. Slowly, because of Dark Hazard, Jim is sucked back into gambling. After losing all his money again, Jim sheepishly visits Marge, who has been living with her mother during the months Jim has been following the races. Although she is planning to divorce Jim and marry Pres, she agrees to give their marriage another chance because of their baby boy. Pres finds Jim a job, but one day when Jim is at the race track, Dark Hazard collapses on the track. Jim offers to buy the injured dog and brings him home despite Marge's disapproval. When he discovers that security-conscious Marge would rather be with Pres, Jim agrees to a divorce and leaves town with Dark Hazard. He nurses the dog back to health and Dark Hazard starts winning races. Once again, Valerie re-enters Jim's life, and the two old pals are reunited.