Duncan is in the throes of a mid-life crisis and searching for his own identity. His problems seem no different than other men facing the same issues, but as he struggles through a divorce and the challenges of co-parenting his children, Duncan soon realizes that he feels complete inside only when he begins to secretly explore a world of torture and death—a world that only he controls. Suddenly, Duncan's life is no longer normal at all. As Duncan deals with his newfound guilty pleasure of destruction and wickedness, his diary entries reflect a roller coaster psychological journey. Duncan grapples with the ramifications of what he is becoming, but at the same time, graphically describes the deaths of several of his victims. Clearly a man caught between his morals and an evil calling. Duncan leads a seemingly typical life during the day, but in the dark of night becomes a monster. Only one man suspects what Duncan is capable of—his best friend, Sudhir, a detective in the Palo Alto Police Department. Despite Duncan's cries for help penned on the pages of his diary, he becomes a master at hiding his transformation from "the guy next door" to a masterful serial killer.