Johnny Casar (Mickey Rooney), a moody and angry young man, lives at a Catholic orphanage run by a kindly priest (Pat O'Brien). After running away one night, Johnny lands a job as a dishwasher. One afternoon he attends a roller derby match and catches the eye of skater Mary Reeves (Beverly Tyler). Under her training, Johnny becomes a world-class skater whose talent is rivaled only by his arrogance. As he womanizes and bullies his way to the top, Johnny's health takes a turn for the worse.