Madeleine Villardier is terribly superstitious, and she's in a lot of trouble for the New Year's Eve party she's planning. Inexorably, the number of guests is down to thirteen. To add to her dismay, the presence under her roof of a certain Consuelo is proving cumbersome, especially as this lady has revelations to make about Antoine Villardier's stormy past. The mistress of the house's trances alternate with marital explanations. But why not consider the fateful number as a lucky charm?