An ending that stays with you long after the credits have rolled is a mark of cinematic brilliance and in this respect the conclusion to Robin Hardy’s Seventies shocker is a classic, aided in many respects because it leaves the viewer reeling from its sheer unexpectedness. While investigating the disappearance of a young girl on a remote Scottish island, Edward Woodward’s Christian copper finds himself at the mercy of a depraved pagan ritual that suckers him in as much as it does the viewer. Unforgiving and completely devastating, its barbaric denouement is not easily forgotten.