Louis is a hard working but crazy Paris taxi driver. Today he's finishing work for the summer holiday: his family is going to Spain with his sister-in-law and her family; they're going in the taxi and towing a caravan (trailer). The customs check at the border is pretty thorough, and the two men have some trouble smuggling in the tobacco they need while on holiday. Next to them in the customs hall is a beautiful blonde, who is smuggling a priceless stolen diamond into Spain. Realising that the customs people are suspicious of her, she slips the diamond into Louis' jacket pocket. She has found out where the families are going, so she will find a way to get it back later. Having overtaken them on the road, she pretends to have broken down, and asks Louis for his help, as a ruse to go through his pockets looking for the diamond: but it's not there. In fact he was smuggling the tobacco in his jacket pockets, and has since emptied it all out into a large jar.