Pleins Feux Sur l'Assassin (1961)

Synopsis
Pleins Feux sur l'Assassin is a passable murder mystery by Georges Franju set in the atmospheric interior of an old chateau and involving the heirs to a fortune. The dying man whose fortune it is has played an unusual trick on those who would have his riches. He has hidden himself in a secret room inside the chateau, knowing that his body has to be found before the castle can be passed on as an inheritance. The would-be heirs are caught in a dilemma but decide to turn the venerable structure into a light-and-sound show extravaganza in order to attract tourist money. That is just fine, except a series of accidents among them soon begins to look like murder. ~ Eleanor Mannikka, All Movie Guide