In The Exorcist Effect, Joseph P. Laycock and Eric Harrelson document a feedback loop in which supernatural horror movies stimulate imitations in real life (through, e.g., performances of exorcism, or reports of diabolical cabals), which in turn engender new movies or other media events based on these exploits, which then lead to new imitations, ad infinitum. “The exorcist effect” is their name for this loop, and their study is grounded in a reconstruction of popular culture, mostly American, from the release of Rosemary's Baby in 1968 up through the circulation of Q Anon conspiracy theories today.

The authors develop a theoretical framework for analyzing this synergy between film and culture in the first two chapters of their book. In general terms, their argument is that the horror genre, which from its inception has presented its stories as based on historical events, is more likely than others to influence the way that people interpret the world, often unconsciously. The ambivalence of horror stories as both fictional and also (allegedly) nonfictional texts challenges readers/viewers to critically evaluate their assumptions about the limits of the real. Some go so far as to search for signs of confirmation of horror's claims in the world around them, at which point the tales literally come to life, through various acts of speculation, confabulation, and play.

Laycock and Harrelson begin their analysis of popular culture in chapter 3, where they discuss the crafting and reception of three related films that introduced America to the devil as he is imagined today: Rosemary's Baby (1968), The Exorcist (1973), and The Omen (1976). All of these movies were self-consciously written, directed, and promoted to enhance their verisimilitude. They were also released at a “peak in the secularization narrative” (40) in the United States. The authors suggest that their cultural significance can lie in the discursive space they provided (and still provide) to explore, reconsider, and debate the truth of one of secularism's central assumptions: that literal interpretations of Christian supernaturalism are a thing of the past.

The study turns next to the lives and careers of those who took up the film's challenge to explore the supernatural world for themselves, and, as per the premise of the exorcist effect, discusses the new media that followed in their wake. The first case study (chapter 4) is Ed and Lorraine Warren, a Catholic couple who left their careers as artists to become self-styled “paranormal researchers” even as The Exorcist was first showing in theaters. One area where their legacy continues is in the burgeoning subculture of today's ghost hunting, with all of its attendant television-series spin-offs. The next case study (chapter 5) is Malachi Martin, the one-time Jesuit priest who was defrocked for having an affair, and subsequently reinvented himself as a faux authority on exorcism. Although it was a hoax, Martin's Hostage to the Devil (1976) became the de facto theological and ritual guide for exorcism among his many international readers, including many traditionalist and sedevacantist Catholic priests critical of the Second Vatican Council's modernized theology (chapter 6). One of these was the Italian priest, Gabriele Amorth, who founded the International Association of Exorcists (IAE) in 1990, in the wake of a televised exorcism on American television. In an illuminating instance of popular religion influencing ecclesiastical teachings, the Vatican eventually sanctioned the IAE in 2014.

Laycock and Harrelson next shift their focus to conspiracy theories. Chapter 7 traces a common stock of conspiratorial tropes, including fantasies of an international, diabolical cabal, back to literary and cinematic sources in the late 1800s and early 1900s, as well as to contemporaneous anthropological theories of ancient religious survivals in the modern (and typically rural) world. It also documents the migration of media-filtered demonological narratives into the field of psychiatry, especially through the work of Dr. Lawrence Pazder, whose publicized sessions with a purported victim of Satanic Ritual Abuse set in motion the first Satanic Panic in the United States. Chapter 8 focuses on the expansion of the moral panic to include allegations of the demonic origins of heavy-metal rock music, and the reinvention of the subgenre in response to these charges, with consequences both entertaining and tragic. Finally, chapter 9 reconstructs the rise of Q Anon in 2017 as the latest metastasis, onto the internet, of this single conspiratorial trajectory, which has now of course become politically weaponized.

The authors have done a superb job arguing their case for the relevance of the horror genre, and for popular culture more generally, in understanding the lived religion of many present-day Catholic and Protestant Christians. Further, as their discussion of Q Anon makes clear, the implications of their analysis extend to the health of American society as a whole. The final pages of the book emphasize the importance of cultivating “information literacy” (240) as an antidote to the groundswell of present-day moral panic, but in light of their preceding history, a reader might conclude that this is too little, too late. If it is indeed true that narratives, rather than information, shape human perception and thus drive history forward, then what is needed in addition to information literacy are alternative stories about the occult that reject the demonological hypothesis. These do, of course, exist, notably in the master-narrative of modern parapsychology, which the authors briefly mention in chapter 4, but are perhaps too quick to pass by.

Overall, The Exorcist Effect is engagingly written, painstakingly researched, and deftly argued. As Laycock and Harrelson themselves note, their study continues the work begun by Michael Cuneo in American Exorcism (2001), and joins with such other works as Jason Bivins's Religion of Fear (2008), Douglas Cowan's Sacred Terror (2016), and Sean McCloud's American Possessions (2015) as a first-rate study of religion, the devil, and popular culture in the contemporary United States.