Ten Days' Wonder (1972)

In the French drama of skintrigue Ten Days' Wonder (1972), Charles Van Horn (Anthony Perkins) wakes up to find himself covered in blood in a strange Parisian hotel room. To come to terms with the carnage, he retreats to his grand family estate, asking his old philosophy professor, Paul Regis (Michel Piccoli), to meet and help make sense of the psycho’s damage. Frightened by Charles’s demented daddy's (Orson Welles) and sultry stepmother’s (Marlène Jobert) bad behavior, his prof is soon put off. As Paul attempts to solve the mystery of Charles's cruel killing, he wonders if there is more than meets the eye (and fly!) in this family affair.