René is in bed, where he has hidden the "real" sausage. Michelle arrives to inform him and Edith that the airplane the British airmen are to escape in, is at the back of the local museum, with other antique vehicles blocking its path out of there. However, René is to arrange a display rally of these old vehicles, in order for them to get them out of the way. As a German soldier comes up the stairs, looking for the bathroom, Michelle hides in the bed, cuddled up with René.
Captain Geering comes into Colonel Von Strohm's office with a knife, with which they delicately open their sausage to find the painting inside. Meanwhile, Herr Flick arrives. However, before he enters their office, he gives Helga, in the ante room, some flowers. After she has been allowed to kiss him, he tells her that the sausage he stole from General Von Klinkerhoffen's wardrobe was empty. The colonel and the captain find that their sausage is also empty. Before they can let Herr Flick in, they must hide it, and Hans is eventually forced to hide it down his trousers. He says it has come to his attention that the colonel has given permission for a vehicle rally of old tractors, steamrollers and other similar vehicles. As he is suspicious of it, he orders the officers to "mingle" among them, unnoticed. He himself will watch from a distance.
René is making the table in the backroom, when Maria, disguised as a small boy, comes out from behind the curtains. She says Edith made her disguise that way, until General Von Klinkerhoffen's search party has stopped looking for her. When Edith walks in and find them close together, René explains himself by saying he is flattening Maria's bosom - since small boys do not have "sticky out bosoms". When Maria has left, Edith tells René that lieutenant Gruber is in the bar, looking for René (wanting the painting to copy). René does not want to be seen talking to him and therefore, asks him to come into the backroom. Gruber tells him the colonel is very angry because "his" sausage was empty. However, René informs him that he has the real one - hidden under Fanny's bed. They go upstairs to get it, but as they enter the bedroom, Fanny has started to eat it. Fortunately, she can spit out the peace of canvas she has got into her mouth. She notices that it bears the name of "the Dutch butcher Van Klomp". Gruber assures René that they can "invisibly mend it". As Fanny asks why René brings a German to her bedroom, she becomes very upset, when he tells her that Gruber is his friend. She starts throwing things at him and calls him collaborator and other things. The flashing bedknobs go off just before they have left, and René explains to Gruber that it means Fanny needs to go to the bathroom. As they leave, it is up to the British airmen, who have been hiding in the cupboard, to answer the radio. The message is in French, but fortunately, the French voice asks for them and puts their commanding officer (Hargreaves) and the line.
Yvette is trying to raise enough money for her and René to escape to Paris, by parading in the town square. The German soldiers are not interested in her services, and soon, officer Crabtree comes by to drive her off. As he walks on, he discovers the two airmen in the public toilet in the square and they explain themselves by saying they were wanting a bit of fresh air.
Monsieur LeClerc arrives with a small cart, disguised as a clown. He informs René that Michelle will collect the lawnmower engine and that René is to find 200 feet of elastic, so that the plane can be catapulted into the air. Every man in the town must give up his braces for the cause. As a German patrol is approaching, René goes inside the café, and LeClerc acts a clown by trying to juggle seven clubs at one time (which he fails).
While the officers are telling René that Herr Flick will be observing the vehicle parade and that they will also be there, two men come in and give René their braces. René explains this by saying they have just been accepted into the Grand Order of the Night Owls, where one initially must walk around for three weeks without braces, since owls do not wear braces. The Germans leave, but they are very suspicious and René wants to tell Michelle to call the whole thing off. However, Edith will not hear of it and tells him and the girls of the next part of Michelle's plan. The next morning, they are to be disguised as road workers, near the museum, and when the vehicle rally starts, they will go into the museum, where Michelle will be waiting with further instructions. At that same moment, an extremely old woman, with wrinkles and warts on her crooked nose, enters the café. As they lead her up to the bar, it turns out to be Michelle in disguise. She has come to pick up the wheelchair with the engine and the girls help her outside to it.
The next morning, the café gang and the airmen are mending the road, disguised as rough and dirty road-workers. Gruber (who is to be responsible for leading the rally procession) passes by in his little tank and asks Fanny for the way to the museum. He happens to spot René, disguised as a road-worker, with no shirt on. He accepts René's explanation as to why they are working on the road and then lends him his gloves, so he will not ruin his artistic hands. Meanwhile, Herr Flick and Helga have had a puncture. Helga pumps the air into the tyre while Herr Flick gives the commandments "Pull, thrust, pull, thrust!" When they are done, we are shown the colonel and the captain, who have commandeered a steamroller of their own, to "mingle" into the parade. Herr Flick and Helga, in his staff car, observe the smoke from it.
LeClerc arrives at the road-worker site, driving a gypsy caravan pulled by an horse. He picks up the café gang and take them to the museum.
Gruber arrives at the museum and informs all the drivers that he will lead the procession. The parade is of many antique Edwardian vehicles, such as tractor engines, steamrollers and fire engines. Meanwhile, the officers stop their steamroller at a side road and walk to the parade site, to observe it inconspicuously. Herr Flick and Helga stop his car right in front of the officers' steamroller in order to do the same thing. As the parade starts and all the antique vehicles drive off, the café gang wait in the gypsy caravan by the museum wall for them to leave. When they are gone, they go into the museum.
After the officers have observed the start of the parade, they go back to their own steamroller. Hans drives it, but cannot stop it - accidentally flattening Herr Flick's staff car, which he had parked in front of the steamroller. Behind the flattened car, they manage to stop the steamroller. As Herr Flick and Helga arrive to find the car flattened, Herr Flick commanders the steamroller and they all four follow the parade in it.
Meanwhile the resistance girls and the café gang put the airmen in the plane (which is an old antique Edwardian biplane) attach one end of the elastic (all the braces) to it and the other end to a antique Edwardian motor-car. René and Edith then drive the car to stretch out the elastic. However, when it is stretched, the others are unable to remove the chocks holding the plane up. Edith gets out of the car to push it, but this makes it too light and the elastic pulls the car back into the museum, crashing it into the plane and creating a right mess. The resistance girls disappear into the woods, while everybody else, including the airmen, return to the café in the caravan. However, they happen to leave Edith behind.