A refugee from a Nazi concentration camp is discovered by some boys in WWII Berlin. They provide him with food and help him to continue his flight. Later one of the boys, the son of a communist, is charged with theft, arrested and sent to a concentration camp.

Rudi Prange is released from prison for good behavior. He gets a job in a transport unit but gets involuntarily involved in a smuggling business by a colleague. When two police officers are gun down Rudi becomes the main suspect.

Railway employee Fritz Marr is not regarded well by his superiors. It is the year 1920, and trains regularly pass the railway hub of Erfurt to the East to secretly transport weapons for the fight against the young Soviet Union. Marr knows about this and wants to mobilise other workers to stop these illegal deliveries. To muzzle him, Marr is relocated to a remote rail work construction site.