The murder of prosecutor Adrien Jacquart at the Riviera hotel exposes the explosive secrets of the Pontavice-Caron family: Blanche, his married lover, is arrested; Eugénie, his ex-fiancée, has a son who could be Adrien's; and Giulia, the housekeeper, is hiding a compromising debt. Commissioner Raven leads the investigation, aided by Léonie, who remains determined to prove her father's innocence. But Raoul Delaunay, a shady businessman, seems to be manipulating events behind the scenes. A final twist, however, turns everything upside down and reignites the mystery: Who is Jacquart's murderer?