Whistle and I'll Come to You (1968)

Plot

A skeptical university professor, firm in his belief that every phenomenon has a logical cause, encounters a profound crisis of faith during a holiday in a secluded Norfolk coastal village. His discovery of an ancient whistle on the beach leads him to unwittingly unleash terrifying supernatural forces. As he grapples with inexplicable events that defy reason, the professor's rational worldview is put to the ultimate test, forcing him to confront the dark mysteries that lurk beyond comprehension.