In his will, the late Jérôme Armandy has expressed the wish to have all the surviving members of his family summoned to the Château de l'Etang, in Provence. Firmin, Jérôme's servant, asks Claude, a Montmartre artist, to organize the reunion, to find the sum of 17 million francs which is hidden there (as a child he had been told by Armandy where the hiding place was) and to divide the amount between the different heirs. But a series of odd facts occur: Claude is knocked unconscious as he is busy ...