The film is set during the three days preceding John Lennon’s assassination, focusing on an in-depth examination of Mark David Chapman’s mental state, rather than concentrating heavily on the act of murder itself. The title “Chapter 27” implies an extension of J.D. Salinger’s novel “The Catcher in the Rye,” which consists of 26 chapters. Chapman was fixated on this book and had it with him at the time of Lennon’s shooting.