 An English clergyman named Jennings confides to Hesselius that he is being followed by a demon in the form of an ethereal monkey, invisible to everyone else, which is trying to invade his mind and destroy his life.Hesselius writes letters to a Dutch colleague about the victim's condition, which gets steadily worse with time as the creature steps up its methods, all of which are purely psychological.The title refers to Hesselius' belief that green tea was what unsealed Jennings's "inner eye" and led to the haunting.