When the director, Monsieur Achille Formentin, walks in one beautiful April morning, he is shocked to find the whole museum emptied of its contents - only a bench, the reception desk, and a lowly fern remain. Distressed, he calls the local police, and Aix's examining magistrate Antoine Verlaque sets out to discover the thiefs identity. But it's the most baffling case Verlaque has ever encountered. Why would someone want to steal porcelain dessert plates, some old documents, and a few small paintings? Could this have something to do with the mysterious robbery of Madame de Montbarbon's apartment a few weeks earlier? And how can Verlaque possibly concentrate on the theft when he and his wife, Marine Bonnet, are going to have a baby?