Dear Fatherland Be at Peace (1976)

1964 in Berlin, not long after the raise of the wall that separated the city: ex-prisoner Bruno is chosen by the eastern secret agency to be sent west with a special order. However as soon as he's crossed the border, he reports to the police. He claims his order was to kidnap someone, but he doesn't know who yet. He's forced to continue feignedly. However the east agents don't really trust him and play a double game...