Based on Gordon Wellesly's novel, after they are recaptured, a British agent helps a scientist and his daughter escape again from Nazi Germany.
Czechoslovakia is invaded by Germans. Axel Bomasch (James Harcourt) calls his daughter Anna Bomasch (Margaret Lockwood) they must leave. She is arrested, but he escapes on a plane. In a concentration camp Karl Marsen (Paul Henreid) talks back and is beaten. Anna tells Karl she aims to join her father. At night they escape and take a boat to England. Karl reports to Dr. Fredericks (Felix Aylmer) and for Hitler he is ordered to follow Anna to her father. Anna is told to see Gus Bennett (Rex Harrison), who sings in a carnival but helps her find her father. Gus finds Anna's letter to Karl and suspects she was allowed to escape to lead them to her father. Gus is knocked out. Anna and her father are taken on a boat to a German ship and Karl. Gus tells British intelligence officers he wants to get Bomasch back.
Gus dressed as a German major enters a building in Berlin by giving orders. He asks for an armament report and gets to see Bomasch. Karl asks Anna to persuade her father to work for Germany, but they refuse. Gus says he knows them and offers to influence Anna. He comes to Anna in her bedroom and gets her to go along.
Gus goes with Anna and her father on the night train to Munich on September 3, 1939. Karl goes too. Englishman Caldicott (Naunton Wayne) recognizes Gus on the train. At a stop Karl has them guarded. Gus tells Anna and her father they can take a train from Munich to Switzerland. Caldicott and Charters (Basil Radford) learn that war was declared, and Charters calls about his golf clubs in Berlin. Karl calls to have Herzog (Gus) investigated and learns he was not authorized and must be an enemy agent; but Karl is told to go along. Charters and Caldicott realize that Gus is in danger. Karl watches Gus and Anna try to persuade Bomasch. Caldicott puts a note under a donut. Gus takes it as if to pay the bill and goes to the lavatory. Charters tells Gus they plan to arrest him, and he asks for help. Karl says that Gus is an agent. Gus is flippant, making Anna angry. Charters and Caldicott in German uniforms overcome Karl and escort them with Gus in Karl's uniform. Gus says that Herzog is on the train, and the five take a car. Karl and two Germans are discovered. Karl chases them but gets a flat. Gus puts the four in a tram on wires and shoots at the Germans. Gus is wounded but takes a tram. Karl stops it and recalls it but is shot too. Gus jumps to another car and makes it across to the others.
This suspenseful thriller combines humor with a fantastic
story to please British war audiences at war with Nazi Germany.
The British are able to laugh at themselves, but the Germans take
themselves far too seriously.