Major Hochstetter is upset with all the sabotage that is going on in the area. He believes that it centers around Stalag 13 and he sets out to prove that Klink's camp is behind the activities.
Hochstetter gets a female Gestapo agent, Eva Mueller, to work undercover and start being a girlfriend to Sergeant Schultz. What Eva is trying to do is get information out of Schultz to prove that Klink is running a crooked prison camp and then expose Hogan and his men.
But right from the beginning Hogan suspects that this female may be working for the Germans. When he puts Carter on her trail one evening, she leads him right to the front door of the Gestapo. Now Hogan is going to have to break up Schultz's relationship plus get the Gestapo off Klink's back.
The story was interesting but had one small flaw. Sergeant Schultz is suppose to be married with five kids. We have even been introduced to his wife in a previous episode which made the show somewhat uncomfortable. But perhaps I am reading too much into this situation and should take the activities as part of a TV sitcom. Even with this small flaw the episode still was a nice show.