The prisoners create an elaborate underground ruse to fool a German spy that has been placed in their ranks.
Hogan must reverse course when efforts to make Klink look competent before the Nazi Inspector General get the Kommandant promoted with a transfer to Berlin.
Hogan's efforts to help a German baroness to escape are thwarted by Klink, who has arranged for the transfer of a British prisoner who is senior to Colonel Hogan.
Again Hogan uses Klink to deliver information to the Underground but Klink is arrested by the Gestapo for treason on other grounds. Thus Hogan and his men must find a way to free Klink before the Gestapo finds the info on him.
Hogan has a touchy mission to deliver ammunition to the underground.
