Le Jeu de la vérité (1961)

A dozen elegant people are gathered in a writer's desirable mansion. In the grand tradition of Agatha Christie, they all have something to hide.They begin a cruel game of truth, a game where you're not supposed to tell lies. As the questions become more and more intimate and precise, the tempers rise, while outside the storm is raging. Enter a hateful person (played by Paul Meurisse, the nasty headmaster in "Les Diaboliques") who seems to know a lot about them. Someone is murdered. Whodunit?