House of Hollow is a young adult fantasy/horror-thriller novel written by Krystal Sutherland and published in 2021. The protagonist, 17-year-old Iris Hollow, went missing for one month 10 years ago along with her older sisters Vivi and Grey. When Grey goes missing again years later, Iris and Vivi trace clues to find her, which lead them to a supernatural place between life and death called the Halfway. Grey, and the Halfway, have the dark, life-changing answers about the Hollow sisters’ true past. Among other accolades, House of Hollow was a 2022 Bank Street Best Children’s Book of the Year, a 2021 New York Public Library Best Book Pick, and the March 2022 Barnes & Noble Monthly Pick.

This guide is based on the 2021 hardcover edition published by G. P. Putnam’s Sons, an imprint of Penguin Random House.

Content Warning: House of Hollow depicts attempted sexual assault, body horror, gore, murder, and suicide.

Plot Summary

High school senior Iris Hollow wants a normal life after her traumatic past. Ten years ago, at age seven, she and her older sisters, Vivi and Grey, went missing on New Year’s Eve; they vanished into an old, burned-down building with a freestanding door. Their parents, Cate and Gabe, were distraught. After a month, the siblings reappeared with no memory of their time away. The girls’ father, Gabe, insisted they weren’t the same, as their dark hair turned white and their blue eyes turned black. Iris, Vivi, and Grey spoke only to each other, sharing a supernatural bond, and developed the ability to manipulate others through touch. Though Cate tried to calm him, Gabe eventually died by suicide, certain his daughters were imposters.

Ten years later, Vivi comes back home to London for her band’s latest gig, and eldest sister Grey—now a famous model and fashion designer for her House of Hollow brand—plans to join. Iris is excited but knows her sisters will bring strangeness. Soon, a bizarre, bare-chested man wearing a bull-skull mask begins stalking Iris.

When Grey uncharacteristically doesn’t show up for Vivi’s show, Iris and Vivi follow clues, such as secrets underneath Grey’s floorboards, to the site of her covert London apartment. There, they find a rotting corpse with carrion flowers, and a man with a bull-skull head attacks them. He shoots Vivi, but the sisters escape. Iris pulls carrion flowers from Vivi’s wounds.

Iris and Vivi seek out Tyler Yang, Grey’s model boyfriend, who thinks Grey is faking her disappearance; Grey vanishes for days at a time. Soon, the three find more clues—including sketches in Grey’s notebook of an abandoned house—that lead them to Grey’s second secret apartment. Iris and Vivi sense Grey’s essence through the wall, pleading with her to appear. A wounded Grey escapes and yells at her sisters to run. The group rushes to the hospital, where the doctor states that Grey is experiencing a psychotic episode in which she believes a bull-man dragged her into another world and is hellbent on finding the sisters.

The bull-man and some rotting, black-toothed people attack the group in the hospital. Grey kills a few of the creatures with a scalpel, and the group narrowly escapes. She uses her intoxication power to persuade a man to drive them to an unknown location. In the car, Grey falls unconscious and feverish. Rotting worms, greenery, and decaying leaves coat her throat. When the group arrives at the home of a small girl named Agnes Young, the driver says the girl owes Grey. Agnes cures Grey with a witch’s brew.

When questioned, Agnes describes a place called the Halfway, where everything is caught between life and death. Grey learned how to travel back and forth from the Halfway using portals—freestanding doors—and her unique blood painted in runes. Agnes was once caught in the Halfway, and Grey saved her. The former insists that Iris and her sisters aren’t human, and that the Halfway lives in them.

The bull-man overpowers the group at Agnes’s house, kidnapping Vivi and Grey. He leaves Iris and Tyler injured, and Agnes dead. Desperate, Iris travels to the place where her sisters vanished, waits for the liminal time of sunset, and steps through a door to the Halfway with Tyler. Lost souls become a part of the eerie world, turning into dead leaves and worms among other forms of decay.

Iris and Tyler find the dilapidated house from Grey’s sketchbook in the Halfway. The former’s memory flashes, remembering Grey with a knife and blood. A trap door inside the house holds the three coats the sisters wore when they vanished. Outside, three grave markers show the names Grey, Vivi, and Iris. Iris and Tyler connect the pieces: She’s not Iris Hollow.

In a showdown with the bull-man to save Grey and Vivi, Iris recognizes him as Gabe Hollow, who refuses to let go of his lost girls. He skins Tyler alive and wears his skin, telling Iris that he’s doing the same thing Grey did to his real daughters. Iris sobs but convinces Gabe to move on to the afterlife, saving her sisters. Grey mourns Tyler, binding him to the Halfway with her grief.

After they leave the Halfway, Iris confronts Grey, who confirms the truth—that she lured the three Hollow girls into the Halfway, skinned them, and stole their skin. Unbeknownst to Iris and Vivi, the original Iris and Vivi were replaced by them, Halfway changelings, whose two layers of skin hide the rotting flesh of the original girls (which explains their memory loss upon being “found” 10 years ago). Grey doesn’t recall her and her sisters’ pasts (not even their deaths), but says she did what was necessary to give them a second chance at life. Iris and Vivi are shocked, and refuse to associate with Grey anymore.

Iris and Vivi attend Tyler’s funeral and settle into life with their mother, Cate, who learns the truth of her daughters’ demise, but loves the changelings anyway—except Grey, whom she calls a “thing” for murdering her children. Cate tells Iris that she’s been her mother for 10 years and can’t help but love her. Iris and Vivi then take a trip to the Halfway and search for Tyler’s soul. Iris thinks it’s unfair that the Hollow girls and Tyler died while Grey survived. She feels confident that they can rescue Tyler, realizing she’s stronger and stranger than she ever believed.