On War (2008) on Netflix

Plot summary

Bertrand, a film director, is researching his next project and asks a funeral director to let him stay behind after closing. He climbs into a coffin and the lid falls shut, trapping him there until morning. The night leaves him profoundly affected. He thinks about hiring a prostitute but cancels when a film on television holds his attention instead, and he keeps ignoring his girlfriend, Louise. When he returns to the parlor the next evening, a stranger named Charles breaks in and asks about the coffin, then leads him to a countryside mansion. It is the headquarters of a cult called The Kingdom, whose leader, Uma, tells Bertrand that pleasure requires joining their war.