A plane goes down and the pilot bails out. Hogan and Co go out to intercept the pilot before the guards do. They find a man who appears to be Colonel Crittendon. But they are forced to let him go because Schultz is too close. To their surprise, the man greets Schultz as a comrade. On the coffee pot, they learn that the man is a near look-alike of Crittendon, Sir Charles Chitterly. Chittlery is a traitor and member of the Cliveden Set (British right wing upper class network with Nazi sympathies). Chitterly says he is on a top secret mission for Hitler. Orders from Berlin are to give him every courtesy until Hitler sends an envoy, General von Schlomm, for him.
The word from London is that they have no idea what Chitterly's mission is, but Hogan and Co are to stop him at all costs. Noting Chitterly's resemblance to Crittendon, Hogan has Crittendon brought to Stalag 13 to impersonate Chitterly. Crittendon is hesitant, but changes his mind when he sees a photograph of Chitterly's wife, Leslie.
As Hogan does not know what Chitterly's mission is, he dispatches Carter, posing as von Schlomm, to find out. Carter fails, so he and Hogan kidnap Chitterly and take him down the stove tunnel. Then the real von Schlomm arrives. He is puzzled and angered by the strange goings on (caused by the fake von Schlomm) and threatens Klink with the Russian Front.
Crittendon takes Chitterly's place. Leslie arrives and nearly stabs him in the back for being a 'filthy traitor'. Hogan stops her, and when he explains, she agrees to help. She tells them that Chitterly's mission is to send terms of surrender to England. Even if England does not agree, it could hurt politically as Chitterly is a member of the Cliveden Set. The news is radioed to London. Their orders are to play along and see what turns up. Hogan is chagrined by this piece of advice.