The deep blue sea of the Côte d'Azur

A young fisherman is found dead, with a farewell letter to his beloved in front of him. When Duval realizes that the beloved is Nicky, the wife of his longtime enemy Louis Cosenza, he becomes suspicious. What initially appears to be suicide may not be so at all. Duval begins the investigation, and soon more and more people come under the police's scrutiny. Among them is Cosenza's son, as well as Patrick, a former skipper. Duval approaches the solution to the case along different paths. And there are also surprises in store for him personally: he finally learns the secret that connected his father to Cosenza.