Young Kuttel belongs to a group of working-class children who live in Berlin at the beginning of the 1930s. In the big summer holidays in 1931, the children want to make a race with their model boats and choose as a venue for the small artificial water in the park of their neighborhood. All children in the area are invited to participate in the competition. But there is a traitor among them, who tells the company to the local police officers, who in any case look with arrogance on the "Reds"...

The "Concordia" trading company in Würzburg is a secret headquarters of the MID, a secret service agency of the US Army. For years, espionage, sabotage, and diversion operations originated from here in order to undermine the Socialist Republic of Germany. A favorable moment for a military attack approaches and plans are developed. These plans are placed in the hands of Major Collins, who keeps them in a safe. Hansen has worked for him for many years, but also for the Stasi as a double agent. Security Chief Colonel Rock knows there is a leak, but Hansen has passed every test thrown at him. He is trying to deal with his current assignment: acquiring the plans so they can be made public. His mission is to get them out of the safe and into the GDR without getting caught.

After years of drifting around, Willi Palko arrives in the lignite mining area. He was not only looking for a new job, but also wanted to finally settle down here. The party leadership sends him to the Schepp brigade, which has made itself "suspicious" (on paper) due to its extremely high production figures. The stranger is accused of being a spy for the factory management. Willi finds it difficult to assert himself, but he is taken with the big excavator, the prospect of one day being allowed to drive it, and the brash flapper Hanna. He stays, and with his help a mine foreman is exposed as a Western agent and coal production is brought up to a really high level.