Fear in the Night (1974)

It took Peggy Heller a long time to recover from the trauma of a brutal physical assault, suffered in her youth. When she married Robert, he provided her with the love and reassurance she craved for and the two settled down in a pretty house in the grounds of the public school where Robert was a master. But the headmaster of the school is not what he seems and Peggy is convinced he means to harm her - is her fear a figment of her tortured imagination or are there forces at work that intend to manipulate her anxieties with fatal consequences?