The Minerva Mines Company is interested in transporting two particularly valuable diamonds from Cape Town to Amsterdam. To confuse potential thieves, two detectives are sent on two different ships with steel suitcases and they have no clue whether they’re carrying pebbles or diamonds. Nevertheless, a collection of questionable characters come on board both ships. The hunt for the diamonds begins; the suitcases are stolen; everyone is suspect.
Reflecting the filmmaker's passion for automobiles, who in his youth participated in car races, the film portrays the attempt to manufacture a new model in the Ford factory in the city of Porto.
In the village of Sableuse, the local manor has been bought out by a nouveau riche, Emile Cousinet. When his wife Lisette, a former music hall actress, flees to Paris with young Pierre de Sableuse, Cousinet asks Father Pellegrin, the village vicar, to bring the lost sheep back home.
