Stephen and his friends Linus and William, all in their late teens, loitering out all day with nothing to do. They steal cars' radios for a living. Previously, they are unduly provoked by an instructor at a Cadet School, the three decide to get revenge and steal the car's radio of that Instructor. However, they get caught. Leung, another probation officer, requests to take on their case. Leung is a kind man who loves cycling, he hopes that he could inculcate them an interest in cycling. Stephen falls in love at first sight with Cindy. At the same, Tommy, a leader of the Cadet School cycling team also crazy about Cindy. Problems between the two boys arise and the instructor at the Cadet School insults Stephen and his friends in front of everyone. The boys vow to take their revenge. Leung convinces them to suppress their anger and hold a bicycle competition so as to regain their self-esteem. Before the race, Linus is injured and is unable to participate in the competition. Cindy suddenly decides to ride in Linus's place in the race, making Tommy's dismay. During the race, Tommy attempts to pull a few fast ones, but will he stop Stephen from coming in first place? (Joy Sales)