Henri Langlois has upset our relationship with the cinema. An exuberant and passionate character, he never ceased to collect film reels and all possible documents in all possible places. If the films had to be preserved, all the films had to be preserved, even if it meant taking enormous risks, even under the German occupation. In a happy mess that aroused so much creativity and enthusiasm, Langlois provoked a completely new craze around his great project: the cinematheque and the film museum, soon to be set up on rue d'Ulm and in Chaillot. More than a film club, the cinematheque was from 1936 to 1976 a school, a refuge for filmmakers and a place bubbling with inspiration and creation. A cinephile rather than a cinephagist, the character is, according to Jean Luc Godard, first and foremost a producer because he produces the vision of the films. This film offers an extremely well-documented portrait, rich in precious testimonials, of this key figure in the history of cinema. From the first rescues of reels in cellars or gardens to the famous Langlois Affair, which became a matter of state, the whole adventure of a lifetime is told here.