Young Kuttel belongs to a group of working-class children who live in Berlin at the beginning of the 1930s. During their summer holidays in 1931, the children want to host a model boat race. As a venue, they choose a small water basin situated in their district′s park. Every child from the neighborhood is invited to participate. However, there is a traitor among them who tells the police about the race. Since the police mistrust the socialists anyway, they immediately come into action and stop the harmless child’s game. The policemen drain the water from the basin and detain Kuttel, the ringleader and initiator of the race, along with his friend Wally. This extreme reaction alarms both the Communist Youth Organization and the Communist Party of Germany. Due to the laborers massive protest both children are released. Eventually, they can even hold their highly anticipated boat race.