Innocents with Dirty Hands (1976)

Saint Tropez. Julie Wormser and her lover, writer and neighbour Jeff Marle, plan the murder of her wealthy husband Louis, an alcoholic impotent. She hits him, and leaves the rest of the task to Jeff. Julie finds herself alone the following day, and becomes therefore the prime suspect. Where is Louis' body? Where is Jeff? Is there any secret beyond a door?