As adults, best friends Julien and Sophie continue the odd game they started as children -- a fearless competition to outdo one another with daring and outrageous stunts. While they often act out to relieve one another's pain, their game might be a way to avoid the fact that they are truly meant for one another.

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.

Stumbling across an uncompleted 1939 film called "Princess Marushka", filmmaker Sam becomes intrigued with the young actor Sylvain Marceau, who last appeared in the film. Hoping to discover the mystery behind Sylvain's disappearance, Sam decides to make a documentary and sets off to interview those who knew Sylvain, including elderly Lisa Morain. Through her interview, Sam learns the story of Lisa and Sylvain's doomed love affair on the eve of World War II.