In this humorous episode, we have Stalag 13 as the meeting ground for a large Luftwaffe military strategy session that involves top secret material. Since the meeting is happening in the recreation hall, and the SS is in charge of security, there is no way that Hogan can listen into the conversations.
But just earlier in the day Klink had given the prisoners a recording device so that they could send messages back to their relatives. Hogan, with the help of the singing Schultz, will place the device in the hall so that the secret meeting can be recorded. However, right when everything looks like the plan will come together, Klink wants Hogan to record his violin quartet with the equipment.
There are some funny scenes in this episode as we get to hear Schultz sing 'Swanee' and Klink (who really is a fine player of the violin) play some Mozart. The story was interesting which played out well on the screen. But be prepared for one of the funniest moment that comes right at the end- Klink playing the 'US Air Force Anthem. Good watch.