Paris is in mourning. At the firework display marking the Dauphin's marriage to Marie Antoinette, hundreds of people have been injured or crushed to death. Yet not all the victims died accidentally. The tragic incident on Place Louis XV yields a new case for Commissioner Le Floch when a strangled woman is found amongst the other corpses. The investigation takes him to the home of a furrier on Rue Royale where he must deal not just with its curious residents but also face the terrifying forces of the supernatural.