 Joseph, Julius and Albert escaped prison on Devil s Island. Loitering around the port, awaiting a ship to take them away, they decide to steal some goods from a merchant. Letting him hire them to repair the roof, they can take insight into the private life of his family. Isabelle, the 18-year-old daughter of the couple, is still unmarried and longs for her old love Paul, who is back in Paris. Felix, her father, is afraid of cousin André, who owns the shop and will fire him if there are no black numbers to be reported soon. A little later, Paul and André arrive on the island surprisingly - and are far less sympathetic than the family expected. But there still are Joseph, Julius and Albert. And not to forget Adolf, the little poisonous Viper Albert carries around in a basket constantly.