Carl Streator, a middle-aged newspaper reporter haunted by the deaths of his wife and infant daughter, discovers that an obscure poem has the power to kill anyone who hears it. His investigation draws him into an unlikely alliance with a ruthless real estate agent, her young secretary who practices Wicca (a modern witchcraft-based religion), and the secretary's radical environmentalist boyfriend. Together, they embark on a cross-country road trip to destroy every copy of the deadly poem and locate the ancient grimoire, or spellbook, from which it originated.
The novel opens with a prologue introducing Helen Hoover Boyle, a real estate agent who profits from reselling haunted houses. Properties plagued by phantom messages and spectral phenomena drive out their owners, who grant Helen confidential listings. Her secretary, Mona Sabbat, checks properties for supernatural activity but is forbidden from resolving any hauntings. The narrator, not yet identified, calls Helen "now dead but not dead" (6) and declares this a possible love story in which everyone is simultaneously haunted and haunting.
Carl then establishes the novel's non-linear structure. Writing from a roadside diner in New Mexico, he is traveling with the Sarge, an old Irish cop, tracking tabloid miracles he identifies as magic rather than divine intervention. The real story, he says, is how they all arrived at this point.
Flashing back, Carl recalls his newspaper assignment: a series on sudden infant death syndrome (SIDS). Riding along with paramedics, he visits the homes of dead infants and notices a library book called
Poems and Rhymes from Around the World open to page 27 at scene after scene. He tears out the page and discovers an eight-line African "culling song," historically sung to end the suffering of the dying or of children during famines. To test his theory, he reads it aloud to his editor, Duncan, one evening. Duncan is found dead days later, confirming the poem kills.
Carl's private life is defined by compulsive isolation. He builds intricate miniature model houses and stomps them to pieces. He reveals that years earlier he read something to his wife and daughter one night and they never woke up. He ran from his old life.
Tracing county records, Carl finds that Helen's infant son, Patrick, died roughly 20 years ago. He confronts her, but she refuses to engage. Through paramedic John Nash, a paid informant, Carl also learns that newlyweds Baker and Penny Stuart were found dead after Helen called their hotel suite; the Stuarts had planned to demolish a historic house she wanted preserved. Carl confronts Helen in a labyrinthine antique warehouse, where she proposes they search for the grimoire, arguing it might contain spells to raise the dead or grant immortality. She warns that the power to kill always corrupts. Carl refuses.
His refusal does not last. The culling song fires through Carl's mind reflexively whenever he is irritated, killing strangers involuntarily. He visits Helen's office and formally meets Mona, who recognizes the spell and explains that someone with intense bottled-up emotion can kill just by thinking it. At a Wiccan ritual, Carl meets Mona's boyfriend, Oyster, a provocative young activist contemptuous of Carl. Carl conceives the idea of the four of them traveling together to destroy remaining copies and find the grimoire.
The road trip takes them across the country, destroying page 27 from library copies at each stop. When books are checked out, Helen and Carl pose as salespeople to gain entry to homes. During night drives, Helen reveals her backstory: She was a cosmetics saleswoman when her infant son died after she unknowingly read him the culling song. She tested the poem on her abusive husband, and he died. She insists Patrick is preserved in cryogenic suspension at the New Continuum Medical Center and believes a grimoire spell might restore him. Carl also discovers Helen is a professional assassin who kills remotely via the culling song in exchange for jewels.
Tensions sharpen as agendas diverge. Oyster wants the grimoire to cull the human population. Helen wants it to heal Patrick. Carl wants to destroy it. Mona wants it for its spiritual significance. Oyster burns a massive used bookstore containing copies of the book, killing two security guards before setting the fire.
In a painful flashback, Carl reveals the full truth about the morning his wife and daughter died. He woke beside his wife, Gina, and had sex with her before going to work, not realizing she was already dead. He kissed infant Katrin without noticing she too had died. The police report noted signs of postmortem sexual intercourse, the same detail now linked to fashion model murders Carl suspects Nash of committing with the culling song.
At a carnival, Mona discovers the grimoire has been with them all along: Helen's daily planner, bound in ancient human skin bearing a pentagram tattoo, contains spells written in invisible ink beneath her everyday notes. Oyster attacks Helen outside a library, trying to steal a burning page of the culling song. Helen slashes his cheeks with her car keys, leaving parallel scars that match those later seen on a figure called the Roadkill Jesus Christ, who resurrects dead animals along an Oregon interstate in the novel's present-day chapters. Helen expels Oyster from the group. Mona stays.
Helen translates the grimoire, uncovering flying spells, occupation spells that project one person's consciousness into another's body, and scrying spells used to perceive hidden or future events. She demonstrates the flying spell, and she and Carl make love for the first time while floating inside a chandelier. Carl falls in love, but Mona warns him Helen has cast a love spell and his feelings may not be genuine. Mona also reveals that Helen and Carl have each told her they might need to kill the other.
Unable to distinguish genuine desire from enchantment, Carl decides to confront Nash and surrender to police. At a bar, Nash has already killed everyone inside using the culling song, which he obtained from the Library of Congress, a permanent archive that cannot be raided or destroyed. Nash tries to read the song to Carl, but Carl's reflexive recitation kills Nash first. Carl waits for police.
Carl is arrested, but the Sarge, whose body Helen has occupied using the occupation spell, rescues him. Mona then warns Carl that Helen may do something desperate. At the New Continuum Medical Center, Carl finds Helen amid smashed jewels and spilled drain cleaner. She appears to have drunk the caustic liquid and unplugged Patrick's cryogenic unit. But Helen's body speaks in Oyster's voice: He has used the occupation spell to possess her. Controlling her hands, Oyster smashes the thawed body of baby Patrick against a steel cabinet, then releases Helen's consciousness back into her ruined body. Helen discovers Patrick's destruction and is devastated. Carl sings the culling song to her as a lullaby, a mercy to end her suffering.
Interspersed throughout the narrative, present-day chapters show Carl and the Sarge tracking grimoire-linked miracles: a mutant ivy destroying Seattle, a talking cow converting a Nebraska town to Hinduism. The Sarge displays unusual intimacy, asking Carl "Do you still love me?" (194), hinting at a hidden identity.
In the final chapter, Carl reveals that before dying, Helen transferred her consciousness into the Sarge via the occupation spell. They now travel together, hunting Mona and Oyster across the country. Carl has called his estranged father for the first time in nearly 20 years, giving his real name and listening as his father cried. Mona and Oyster possess the grimoire and multiple spells, including a shield that protects them from the culling song. However, Mona slipped Carl the grimoire page containing the culling song along with a handwritten note suggesting she does not share Oyster's apocalyptic aims. Carl acknowledges the power has shifted to the younger generation. Helen-as-the-Sarge takes out a pistol and suggests they kill Mona and Oyster the old-fashioned way.