Benoît is a coward and a voyeur, who gets his kicks from watching other couples make out. He cajoles his two new companions to attempt what he has never dared do: rob the safe in his father's factory, seduce his stepmother to blackmail her for money and finally go so far as committing murder. Thus begins a wild ride that takes them to the very edge of madness.

In 1964, Henri-Georges Clouzot's production of L'Enfer came to a halt. Despite huge expectations, major studio backing and an unlimited budget, after three weeks the production collapsed. This documentary presents Inferno's incredible expressionistic original rushes, screen tests, and on-location footage, whilst also reconstructing Clouzot's original vision, and shedding light on the ill-fated endeavor through interviews, dramatizations of unfilmed scenes, and Clouzot's own notes.