A Head Full of Ghosts by Paul Tremblay (2015) is a horror novel published by William Morrow. It is the fifth of Tremblay’s 10 novels, and was optioned in 2016 by Focus Features for screen adaptation. His seventh novel, The Cabin at the End of the World (2018), winner of the Bram Stoker and Locus Awards, was also adapted for the screen; it was released in 2023 as the M. Night Shyamalan film Knock at the Cabin. Tremblay received another Bram Stoker award for his novel Disappearance at Devil’s Rock (2016) but considers one of his highest compliments to have come from Stephen King, who tweeted that A Head Full of Ghosts “scared the living hell out of me” (Breznican, Anthony. “Stephen King at 70: A Head Full of Ghosts Author Paul Tremblay on Empathy in Horror.” Ew.com). Tremblay attributes the significant increase in attention and readership of his novel to this praise.

Tremblay is a native and resident of Massachusetts, where most of his fiction is set, and has a master’s degree in mathematics. He is a lifelong horror fan, and has served as a member of the jury that selects the winners of the Shirley Jackson Prize since the award’s inception in 2007.

This guide follows the 2016 P.S. paperback edition of A Head Full of Ghosts.

A note on naming and phrasing: Marjorie and Merry’s parents are named Sarah and John Barrett, but throughout this guide, they are referred to as Mom and Dad to create continuity for the reader, as their first names are rarely used in the novel.

“Documentary” is placed in quotes when referring to the so-called documentary The Possession throughout this guide; this is to emphasize the distinction between educational, integrity-driven programming and media which uses obfuscation, manipulation, and deliberate editing in favor of entertainment over accurate recounting of events. “Reality” is similarly referenced. This decision is rooted in the emphasis that the novel places on the ambiguity surrounding memory, and the ways in which trauma, personal motives, mental health, and individual perspectives dictate the ownership of a narrative and shape its legacy.

Content Warning: This novel contains graphic descriptions of murder, death by suicide, mental health conditions, alcohol addiction, and mentions of sexual abuse, infanticide, anti-gay slurs, and self-harm. The text also draws on unscientific and stigmatizing literary traditions that connect mental health conditions with the supernatural.

Plot Summary

A Head Full of Ghosts centers around a series of interviews between 23-year-old Meredith “Merry” Barrett / “Karen Brissette” and author Rachel Neville. Rachel is researching a nonfiction project on the subject of the infamous documentary The Possession, which presents Merry and her family as its subjects, and the subsequent apparent “murder-suicide” of Merry’s parents and sister. Interspersed throughout the novel are blog posts written by someone calling herself “Karen Brissette,” who is later revealed to be Merry herself writing under a pseudonym.

Merry shares the events as they unfolded according to her self-professed compromised memory. As she does so, Rachel begins to realize that she cannot trust Merry, whose recollections emerge as influenced more by personal motive and the desire for attention than a sincere effort to recall events as they happened.

Merry describes events 15 years earlier, when her sister Marjorie Barrett, who was then 14, began manifesting strange and frightening behavior, such as acute onset paranoia and psychosis. Their parents sought treatment for her with a psychiatrist. Marjorie’s disinclination to participate, based largely on objection to the effects of her medication and the family’s financial struggles, presented significant obstacles. Stress in the house contributed to Marjorie’s feelings of insecurity and fear; the parents often argued, rarely bothering to hide their disagreements from their daughters.

The father, fired from his job at a toy factory, had been out of work for 18 months, and though the mother continued to work at her job at a bank, the family was facing foreclosure. The father began attending church while claiming to be out looking for a job, later confessing to his wife that not only had he not been diligent in seeking work, but he had taken their daughter to see his priest without her consent. His religious fervor resulted in the church’s involvement as Marjorie’s symptoms began to worsen. Merry was one day informed that their family would begin filming a “documentary” for the Discovery Channel chronicling the exorcism that their father’s priest planned to perform on her sister. Self-involved, attention-seeking, and lacking in empathy which should have been present in a child of her age, Merry relates the story as an adult with the same kind of jocularity and detachment.

Merry confesses to Rachel that she is the author of a horror blog. She invites Rachel to read it, particularly her entries on The Possession, about which she writes as if she were a third, uninvolved party. Merry disclosed that her sister confessed that she could distinguish between the voices she heard and a demonic presence, and that she was deliberately acting out in hopes of helping the family by making the “documentary” sensational. Merry describes how the presence of the film crew added to the stress in the household, and how the production crew and the church eventually abandoned the family when Marjorie’s exorcism ended in the assault of a priest and Marjorie intentionally leaped from their upstairs balcony. After staying in a hospital, Marjorie came home. Despite visits from a state-appointed psychiatrist, she continued to experience symptoms of her mental health condition.

In the climax of the novel, Merry reveals to Rachel and the reader how she participated in the poisoning of her parents and sister, claiming that her sister had tricked her. At the close of the novel, Rachel confesses to being unsettled and confused by Merry’s story and her behavior. Merry saunters off, unfettered, looking forward to the publication of a book that she believes will be all about her and the financial and attention-based gains she will reap as a result.