[2] The film follows the exploits of a Soviet communist officer,[3] Major Kerimov (Minetti), who is sent to recover a Secret Archive from the Nazis.

He receives immunity from prosecution if, in return, he hands over to them the Gestapo's secret archive, which is hidden on the Elbe River in Meissen.

Upitz has the welder Max Wiesbach taken to an underground tunnel in Riesa in order to seal a leak under water.

Wiesbach is convinced that he has sealed a leak in the secret archive and passes this information on to a staunch communist who is sent to the Soviet front a short time later and defects to the Russians there.

He receives help from staunch communists and is hired as a driver in the factory where Max Wiesbach works as a welder.

His communist supporters make arrangements for the arrival and departure of a camouflaged Soviet cargo plane.

When Kerimov replies that the flight is going to Moscow, Upitz reacts at first amused, believing this is a joke, and then remains speechless.