August 13, 1961: The passengers on the interzonal train from Munich to East Berlin learn 3½ hours before crossing the border that the Wall is being built in Berlin. They have 3½ hours to make a life-changing decision: to get off the train or keep going.
Two families attempt a daredevil plan to escape the GDR with a homemade hot air balloon, but it crashes just before the border. The Stasi finds traces of this attempt to escape and immediately starts investigations, while the two families are forced to build a new escape balloon. With each passing day the Stasi is closer on their heels – a nerve-wracking race against time begins.
East Germany, 1988: working as a state security service agent, Jürgen Kaiser is loyal to the party line, but worried about his son Marco, a punk. As he is arrested after a concert, Marco is forced to join the army, where he surprisingly identifies with socialism and believes he has to defend his country against the capitalist enemy. While Jürgen is astonished, his wife Hanna and Marco's girlfriend Anja, supporting the civil rights movement, don't like his new attitude...