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.
When another dead elderly gentleman is fished out of the Thames, Inspector David Perkins is convinced that the gorilla gang is active again. On a doll found with the body, characters of an African language are discovered. Together with Sergeant Pepper and language specialist Susan MacPherson, the search for the head of the gang begins.
In Berlin in 1961, an American soldier and a German engineer join forces to build a tunnel under the Berlin Wall in order to smuggle out refugees, including the soldier's East German girlfriend.
