The Nazis bring a huge truckload of dynamite to Stalatg 13 and store it in the cooler. Hogan figures the Nazis are storing it there because they know the Allies will not bomb a stalag. This is confirmed by Major Hochstetter over the coffee pot. Hochstetter will not say where the dynamite is being shifted to. But he wants two more things from Klink: a makeshift office in the cooler and two of Klink's men to drive the dynamite. To his horror, Schultz is chosen to drive the first dynamite truck (because he is expendable).
Hogan and Co get to work on Schultz. They learn that Schultz will not be told where he is shifting the dynamite to until he leaves camp; the only clue is one of the guards mentioning Flenzheim Road. Hogan tries Klink, but only succeeds in scaring Klink into taking a furlough to get away from the dynamite.
They figure they could do with extra dynamite. So, together with the Underground, they set up an ambush on Flenzheim Road to hijack the truck and steal the dynamite. But the truck somehow disappears before it reaches their ambush. They are baffled, as there is nowhere on Flenzheim Road for Schultz to turn off. Next morning, a much-relieved Schultz brings an empty truck back to Stalag 13.
The second dynamite truck is made ready, with Corporal Mueller as driver. Hogan learns that it will be going up North Road, and he knows there is a power plant up there. They set up posts on North Road, but this time to see where the Nazis are taking the dynamite. They again lose the truck, but pinpoint a search area. The Underground will search it, and also the woods along Flenzheim Road.The search yields two hidden caches of dynamite; one beside the bridge on Flenzheim Road and the other near the power plant. Hogan orders that they leave the dynamite where it is so as not to alert the Nazis. He figures that Hochstetter is running a scorched earth operation; the power plant and bridge will be blown up in the event of an Allied invasion. He suspects Hochstetter has other such caches, which means he must have a map or chart of their locations. Now Hogan plans to grab it as he is sure London will be interested.
So Hochstetter receives a visit from the fire chief of Hammelburg (Carter) and his secretary (an Underground agent) in his makeshift office. They are there on pretext of a routine fire inspection. While the secretary keeps Hochstetter distracted, Carter sets off some smoke bombs. Hochstetter thinks there is a fire and he panics, because there is still dynamite in the cooler. Hogan and Co use the ensuing panic, confusion, evacuation and fire-fighting to steal Hochstetter's briefcase - they saw him quickly stuff some papers in there. Hochstetter also gets a soaking - and a cold - from the fire hoses.
Hochstetter's map is soon on its way to London. Klink, now returned from his furlough, rewards the prisoners with extra rations for their heroic conduct during the emergency.