''The Heart is a Lonely Hunter'' was Carson McCullers' first novel, written in 1940. Set in a small town in the American South, it is the story of a group of people who have little in common except that they are all hopelessly lonely. A young girl, a drunken socialist and a black doctor are drawn to a gentle, sympathetic deaf mute, whose presence changes their lives. This powerful exploration of alienation is both moving and perceptive.