Madame Lapin, occasionally known as Madame Ralin, is a wealthy Parisian aristocrat during the 1920s-1930s. Her public prominence in high society masks her true role as the head of a far-reaching criminal cartel. This organization conducts major unlawful operations across multiple territories, including France, Spain, and America. Iconic sites like the Louvre Museum, Eiffel Tower, and Orient Express serve as stages for her undisclosed activities. Her international connections surface through interactions with figures like Al Capone during investigations led by journalist Antoinette "Tony" Dubois.

Madame Lapin engages in persistent adversarial confrontations with Tony Dubois and her colleague Alain Pichet, who investigate her empire during social events in Paris and assignments across Europe and America. This opposition establishes her as the primary antagonist against their efforts to expose criminal networks. Her organizational structure relies on loyal subordinates such as her servant Igor, and she enforces leadership through secrecy and discretion. Leveraging her aristocratic status, she evades law enforcement scrutiny, including that of Inspector Calvignac, though their professional exchanges remain undefined.