Lusty defrocked minister Lawrence Shannon (Richard Burton) is a tour guide in Mexico. Leading a tourist group from a Baptist women's college, he finds it difficult to avoid acting on his attraction to Charlotte (Sue Lyon), the young niece of the group's leader, Judith Fellowes (Grayson Hall). When Fellowes swears to ruin him, Shannon strands the bus at a hotel to seek advice from the manager, an old friend. Over the course of one night, the alcoholic Shannon spirals out of control.