The Collector General - S3-E27
Trivia: In this episode, there is a German coat-of-arms on the wall with the bug in it. This is the only time it's seen.
Everybody Loves a Snowman - S3-E14
Trivia: For budgetary reasons, it was not unusual to see one actor play several different characters in a television series. Case in point, in this episode, Noam Pitlik plays the part of an escaped POW. In the pilot episode, he was a Gestapo agent, and various German officers in others.
Answer: It's a solitary cell. Steve McQueen, star of 'The Great Escape' is known as the 'Cooler King'.