The film Helter Skelter is based on prosecutor Vincent Bugliosis 1974 book of the same name (New York: Bantam Books, 1974), in which he details the grisly Tate and LaBianca slayings of August 1969 and the subsequent trial and convictions of the murderers, Charles Manson and four of his followers. Spending several months collecting testimony and evidence and seven more conducting the trial, Bugliosi pieces together who committed the murders, how the murders occurred, and, most importantly, why the so-called Manson Family was thirsty for blood.

As Bugliosi does in his book, the film begins with flashbacks to when the bodies were first discovered, the activities of the Manson Family shortly after the murders, and the questioning of suspects and witnesses by police before linking Manson to the slayings. The second portion of the film is based on the present, or the trial that occurs after all the evidence and testimony have been gathered. During the trial, the film flashes back to the nights of the murders. While some of the less important details of Bugliosis 700-page book are omitted, the film remains true to Bugliosis account. Quotes Bugliosi cites Manson and witnesses as having said are recited verbatim in the film. Yet there is one instance in which testimony given by three separate people in the book is spoken by one person in the film. When, in the film, Paul Watkins explains Mansons Helter Skelter ideology, Watkins is actually stating what he and two other witnesses, Greg Jakobsen and Brooks Poston, told the prosecution. Watkinss voicing his own and others words is clearly a method the screenwriter used to simplify and shorten the film.

Because the film follows Bugliosis account so faithfully, its stance is extremely anti-Manson and pro-Establishment. The family is portrayed in both the book and the film as filthy, drug-crazed hippies, while Manson is depicted as an insane guru with the ability to program human beings. Manson combats these portrayals in his autobiography, written with Nuel Emmons, entitled Manson in His Own Words: The Shocking Confessions of The Most Dangerous Man Alive (New York: Grove Press, 1986), maintaining that he did not influence members of his family, who were innocent children whose parents had rejected them.