Patrick is a tenacious lawyer specializing in environmental law. France is a schoolteacher who becomes an activist after her husband develops cancer from exposure to a pesticide. Mathias is an ambitious lobbyist working for an international chemical corporation. The paths of these characters collide as the lives of thousands are affected by a tragic act that sparks a powerful movement while the corporation fights to prevent the truth from being revealed.
The trawler Marie-Morgane sinks suddenly and inexplicably with all its crew, including Captain Lenormand and his son. When Nolwenn Lenormand hears the news she's convinced that a submarine on maneuvers must have been responsible.