General Von Klinkerhoffen thinks that a mixed marriage between a Frenchwoman and someone from the occupying forces would provide a good propaganda piece for the newspaper. He decides that Captain Bertorelli should marry Edith.
A party is arranged at the chateau so that local dignitaries can meet the 'happy couple'.
The Résistance rescues the airmen from the chateau via an underground river. The airmen end up stuck in a sewer underneath the town centre.Overview from themoviedb.org