On a hot May night, three Cambridge students carry out a ritualistic act that changes their lives. Decades later, none of the participants can remember what transpired; but their clouded memories bind them together. Unable to move on, Pam Stuyvesant has epilepsy and is plagued by sensual visions. Her husband Lucas believes that a dwarfish creature is stalking him, and invents histories to soothe Pam's fears. Self-styled Sorcerer Yaxley becomes obsessed with a terrifyingly transcendent reality. The narrator is seemingly the least affected participant in the ritual: he is haunted by the smell of roses, and his guilt as he attempts to help his friends escape the torment that has engulfed their lives.