Madame Lapin is a prominent criminal figure and the narrative's primary antagonist. She publicly presents herself as a wealthy socialite while secretly commanding an extensive criminal network across Paris. Her illicit operations repeatedly bring her into conflict with the protagonists during their investigations.

Her criminal activities span high-society venues throughout Paris, such as the Louvre, Eiffel Tower, and Opéra Garnier, and extend internationally to locations in Spain, America, and aboard vessels like the Orient-Express. During these ventures, she encounters various historical personalities of the era, including figures like Al Capone and Coco Chanel.

As the head of her criminal organization, she coordinates diverse illegal enterprises. Her leadership establishes her as a persistent threat opposing the protagonists' investigative endeavors across multiple cases. She functions consistently as the central opposing force without significant evolution or revealed backstory across the narrative episodes.