Underground operative Marie Louise Monet (Tiger) has been captured by the Gestapo. London refuses Hogan permission to rescue her. Hogan and Co decide to rescue her anyway, even though it does mean disobeying orders.
Hogan has the men make up some fake wood alcohol, which he shows to Klink, to have him think there is illegal homebrewing going on in the camp. He uses it to trick Klink into calling a special formation at 3pm so he can smuggle an operative, Schnitzer, into the camp. At 3pm Klink is demanding who made the brew while Schnitzer is arriving. The prisoners start a fight to keep Klink distracted while Schnitzer sneaks into the dog kennel tunnel.
Schnitzer tells Hogan that the Gestapo are taking Tiger to Berlin and Himmler has invited Hitler himself to be present at her execution. Tomorrow night they will move her by train to Berlin (also a munitions train). Hogan and Co set up to intercept the train at Hammelburg. They change the signal to stop the train and set off some gunfire to draw the Gestapo out. Posing as the Hammelburg garrison, they tell the Gestapo they are trailing an Underground unit who opened fire on them. The train has been stopped because of this. When Captain Steiger of the Gestapo demands the train be released, they say the track is mined. Steiger is anxious to get Tiger to Berlin and demands to know a safe place to take her. The possibilities are narrowed down to...Stalag 13.
So Steiger brings Tiger to Stalag 13, where he puts her in the cooler under double guard. Hogan cannot get her away from the Gestapo, but of course that does not stop him sneaking in to have some lovemaking with her. He cannot take her out through the tunnel because it would be too risky for their operation as the Gestapo is on alert. Hogan's plan is to take the heat off Tiger by faking her death, but it means allowing the Gestapo to take her back on board the train.
Newkirk, posing as Hammelburg Gestapo, phones Steiger and tells him they have heard about his difficulties. They are sending him two of their men as reinforcements. The reinforcements will meet him at the train, which is now clear to resume its journey. Tiger is brought back to the train and Steiger meets the reinforcements (Hogan and Newkirk). Hogan and Newkirk start by binding and gagging the guards in their compartment. They break into Tiger's compartment, where they bind and gag Steiger and his aide. Then they prime a bomb and leave it in the compartment while they escape through the window with Tiger, where their vehicle waits. The train carries on until the bomb blows it up. Tiger will be smuggled to England.
Klink still means to punish Newkirk and Le Beau for starting the fight. Hogan persuades him not to in exchange for military information he got from the transient prisoner that could end the war. The information is: "Surrender." Klink is not impressed and says, "dismissed!"