A hard-working woman, Alice du Pomeuil owns a prestigious hotel in the center of Paris. Julie, her only daughter and future heir to the establishment, is engaged to Martial Jacquin, a financial analyst in a major investment bank. However, her mother does not seem to take a very favorable view of her daughter's future union. Following an altercation with her daughter, she is found dead in her suite… Alice du Pomeuil was murdered by injecting a lethal dose of Botox. During their investigation, Revel and Rousseau discover that Julie suffers from a psychological disorder which makes her particularly vulnerable to anger. Could she have murdered her own mother in cold blood? Did she act alone or was she manipulated?

A deputy prosecutor in Paris has received death threats. He must now remain cautious. It was by a miracle that he narrowly escaped a parcel bomb which seriously injured the clerk. Revel and Rousseau are immediately placed on this matter. They quickly suspect the deputy's wife, a renowned lawyer, of having pressured a former convict to get rid of her husband, from whom she cannot part without having to pay a heavy pension. Unless the case hides a much more perverse manipulation. Revel and Rousseau are lost in conjectures ...