By orders of General Mueller of the Gestapo, the Gestapo are to take over the running of Stalag 13, with Major Strauss in charge. The Luftwaffe personnel are to be transferred to the Russian Front. Hogan suspects this is all part of the Gestapo's plan to expand their networks into black market operations. Knowing he cannot tame the Gestapo a la Klink, he must find a way to get rid of them or his operation will be ruined. To say nothing of the terrible food the Gestapo is serving to the prisoners.
When Strauss finds a tunnel (actually, a disused tunnel), he sends Hogan to the cooler for a week. There, Hogan formulates a plan to get rid of the Gestapo and passes a message to Le Beau to bug Strauss's phone so they can obtain a sample of Mueller's voice for Newkirk to practise with. Schultz also visits and informs Hogan that he and Klink are equally unhappy with the situation. So when he and Klink hear that Hogan has a plan to get rid of the Gestapo, Klink arranges for Hogan to be quickly released from the cooler. He and Schultz team up with Hogan, who tricks them into taking him to the Hofbrau. He keeps Klink and Schultz distracted with girls while he talks to his contact, Otto. Otto, posing as Swiss civilian Baum, arrives at Stalag 13, together with Mueller's 'aide', Captain Geissler. Newkirk and his imitation of Mueller's voice covers the phone for confirmation of their credentials. They present a fake document, supposedly authorized by Mueller, for the execution of Hitler. They persuade Strauss to sign with promises of a fortune and safe conduct out of Germany. Hogan then has Klink take the document to General Burkhalter.
When Burkhalter sees the document he gives Mueller (who thinks Strauss has set him up) an ultimatum: withdraw from Stalag 13 and reinstate the Luftwaffe, or he will take the document to Hitler. Naturally, Mueller chooses the former and the status quo is restored at Stalag 13. Mueller also has Strauss arrested.
Burkhalter is impressed with the scheme that got rid of the Gestapo and asks Klink how he managed it. Klink tells him that some things cannot be told. When Klink asks Hogan the same question, Hogan likewise responds that some things cannot be told - especially to him.