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.
Corporal LeBeau pretends to be a visiting French scientist while Hogan smuggles out the real one.
Rusted-out plumbing collapses the emergency tunnel just as Hogan needs to get four Underground leaders out of Germany, so he creates a health spa.
