Based on the novel by Carson McCullers, The Heart is a Lonely Hunter stars Alan Arkin as John Singer, who is deaf. Singer moves from a small town in order to be close to his institutionalized friend Antonapoulos (Chuck McCann), who is deaf and mentally impaired.
Singer rents a room with a family whose father, Mr. Kelly (Biff McGuire), is unable to earn a living due to a serious injury. His teen-aged daughter Mick (Sondra Locke, in her film debut) is at first resentful of Singer's presence, but he ingratiates himself by introducing her to classical music (which he can feel, if not hear).
Singer likewise tries to brighten the lives of such unfortunates as alcoholic Blount (Stacy Keach Jr., also making his first film appearance), dying black doctor Copeland (Percy Rodriguez), and Copeland's poverty-stricken daughter (Cicely Tyson).