A gang of petty thieves in the Parisian region has for a long time been trafficking a variety of goods, including alcohol. Le Pépé, the doyen, has just been removed by Don Momo when the latter learns that the gang's turnover has fallen. Worse: the truck that they use to deliver adulterated whiskey has been stolen. Rico, the organization's best henchman, discovers the truth: a rival gang made up of Americans is also interested in running alcohol. Don Momo decides to act and attacks his rivals' nightclub - and fails. The gang even has to pay for damage. The horrible trap invented by Momo is also a flop. It consisted of ramming the "Americans" with Pépé's wheelchair filled with a few litres of nitroglycerine. But is nevertheless Pépé, miraculously unscathed after the explosion, who saves the day by taking out a gigantic - armed - cake destined, in principle, to reconcile Americans and French.