The Ruhr area in November of 1918. 13-year old Achim Wolters and his friends get their hands on some potatoes on the market. They want to surprise Achim′s father, who works on a mine sweeper boat, with a decent meal. But Achim′s father does not show up – an informer at the train station has betrayed him for his left-wing beliefs and has turned him over to the police. The priest tells Achim the sad news and advises him to pray for the release of his father. But when carpenter Stelzebein stresses that everybody has to take actions for himself, the devout boy at first does not believe in Stelzebein′s words. But then Achim witnesses in the prison how brutally the imperial police treat his father and the other inmates. Together with his loyal friends, Achim takes Stelzebein′s side. When the revolution starts, they stand together on the barricades.