On War (French: De la guerre) is a 2008 French comedy-drama film directed by Bertrand Bonello and starring Mathieu Amalric, Laurent Lucas, Guillaume Depardieu, Asia Argento, Michel Piccoli and Léa Seydoux. It follows a man in the middle of an existential crisis as he gets drawn into a strange pleasure-obsessed cult. The film's title loosely refers to the treatise On War, by Carl von Clausewitz.
Bertrand (Mathieu Amalric), a film director, is conducting research for his latest film, and asks a funeral director if he can stay back at his parlour after the close of business. Bertrand cannot resist getting into a coffin, and accidentally knocks the lid down, locking himself in. When he’s released the following morning, it’s clear he’s been profoundly affected by the experience.