Positions danoises (1977)

Mirna is learning a script when Willy (in pilot's uniform) arrives home. They have sex and go off in his car. Maude and Charlie arrive and get in the house by the back door. They are having sex when another couple arrive looking for the manuscript but ending up also having sex. When Maude and Charlie are discovered trying to sneak out, it turns into a foursome. Mika and her partner arrive with similar results, then along comes a redhead, in a white transparent body stocking and cat burglar mask, and begins to search for the manuscript as well. Charlie catches her and she too is drawn into the orgy. Then the first couple come back and catch them all at it.