Inge Karsten receives an unexpected visit from her former student friend Margit from the West. She is even more surprised to hear that she is married to her stepbrother Herbert, who was long thought to be missing and whom she had almost forgotten. He last lived in Canada. This presents Inge's husband Horst, who has an important job as a military pilot, with a conflict of conscience. The situation is even more serious than it seems at first glance. In truth, Margit is an agent and the whole story is a staged game by the West German secret service...

Annekathrin Bürger
as Margit Steiner

Kati Székely
as Inge Karsten

Alfred Struwe
as Horst Karsten

Rudolf Ulrich
as Major Seidel

Herbert Köfer
as Hauptmann Kranz

Jürgen Frohriep
as Major Sander

Ezard Haußmann
as Oberleutnant Kempf

Heinz Behrens
as Leutnant Schütz

Otto Stark
as Helmer

Kurt Müller-Reitzner
as Funker