The true story of a German agent sent to the USA in 1944 in order to stop the development of the atomic bomb.

Margot is looking forward to moving into the old defense tower with her fiancé Lutz, a writer. Then the writer receives the news of his sister's death. Lutz is supposed to take in their children Traudl and Rudi and the dog Leo. Margot did not expect so much attachment...

East Berlin, shortly after the construction of the Berlin Wall. Kurt Schröder and his family dig a tunnel to escape to West Berlin as they struggle to overcome the obstacles blocking their underground path to freedom.