Prologue: The men are putting explosives on a railroad track to sabotage a munitions train. However, when LeBeau spots a German patrol, he tells Hogan and he pulls the men off the job. Newkirk says that the train only comes by once a week, but Hogan insists they go back to camp. When they get back, they see more soldiers in front of the camp that weren't there when they left.
Part One: Hogan has Carter and newkirk cut their way back into camp at a blind spot when the guards leave. They get caught and say that they were breaking out. Klink has them put in the cooler; meanwhile the others get back in through the emergency tunnel. The next day, while trying to get Klink to release Newkirk and Carter, he finds out that the reason Klink had the patrols beefed up was that Burkhalter is coming on an inspection tour. Later, London HQ tells Hogan not to try again, to leave it to the underground. Hogan says that shooting at a patrol would have started a Gestapo investigation and endanger the whole operation. He also insists that they finish the job. Kinch and LeBeau remind him about the last inspection tour Burkhalter had, that he brought his sister Gertrude with him. This gives Hogan an idea to have Klink write a letter to Gertrude asking her to come with her brother on his personal stationary. Hogan has Newkirk forge a love letter in Klink's writing to Gertrude while Carter, in the other cell, distract Schultz with a chocolate bar. When the general arrives, Klink is surprised that Gertrude is with him. At dinner that night, the general leaves early. Klink orders Schultz to stay, but the general orders him to come help him with his boots. Alone, Gertrude says that he reminds her of her first husband who was lost in action at the Russian front. Klink is surprised when Gertrude tells him she likes him.
Part Two: Klink tells Hogan obout Gertrude and asks for his help. Hogan agrees on the condition that if he helps get rid of her, that Newkirk and Carter would be released from the cooler. He suggests that he throw himself into work, to make it look like he would care more about his job than her. However, this backfires in two ways: One, he puts more patrols around camp; and two, this makes him more attractive to Gertrude; she says that women should be second place to a man's job. Klink then refuses to release Hogan's men. This makes Hogan more determined to blow up the train. He suggests that Klink tell Gertrude the truth, that he's not attracted to her. Hogan tells Klink to take her on a moonlight drive the next night: the same night the train is to come by. That night, Hogan sneaks out of the barracks and into the trunk of Klink's staff car. Schultz drives out of camp and by the train tracks; when they arrive there, Klink tells Schultz to leave them alone. When Schultz leaves, Hogan gets out and goes to the tracks and finishes laying the explosives. When Klink tells Gertrude the truth, she calls Schultz and orders him to drive back to camp. Hogan manages to get back in the trunk just before they leave. When they get back, Gertrude leaves in a huff, slamming both the car door and the office door in Klink's face. Hogan gets out and pretends that he is standing alone. Klink spots him and asks why he is out of the barracks. Hogan asks what happened and he says he told her the truth. Hogan doesn't believe it and Klink says that lightning should strike him if he's lying; just then the train blows up.
Epilogue: Burkhalter is angry with Klink; threatening to send him to the Russian front for his treatment of Gertrude. Hogan steps in and says that Klink was saving them embarrassment; that he wouldn't want to present Klink as his brother-in-law to Hitler and his other friends because Klink knows he's not good enough for Gertrude. Burkhalter says that he will discuss this with her, and decides that there's enough trouble at the front. Klink says that he's grateful for Hogan's help, but he doesn't like the things he said. When Hogan says he can get the general back, he changes his mind. He asks how he can thank Hogan, and he says, 'What good are enemies if you can't depend on them?'