Vesper Wright is a cynical, apathetic twenty-four-year-old waitress at Shortee's, a chain restaurant in Westchester County, New York. She left home at eighteen, estranging herself from the deeply religious community in which she was raised, and has spent six years suppressing her emotions and keeping everyone at arm's length. One night, after a customer harasses her and nacho cheese inexplicably explodes in his face, her manager fires her. Walking home drunk, she finds a red envelope on her doormat containing a wedding invitation: Her cousin Rosemary, whom Vesper considers a sister, is marrying Brody Lewis, Vesper's first and only love. A handwritten note reads, "Please come home. Stay for the weekend, or forever. We love & miss you" (18).
Vesper decides immediately to attend, driven by a need to confront Rosie and Brody and by her hunger for some sign that she is wanted. She travels to Virgil, New Jersey, a remote hamlet where her family's Victorian farmhouse stands. Vesper grew up there in the Hell's Gate sect, a Satanist church whose members worship Satan as their Lord. At ten, she realized she did not believe, and at eighteen she left. The church's rule is absolute: Anyone who leaves cannot return, making the invitation a striking exception.
Vesper arrives to find a rehearsal dinner already underway. Her mother, Constance Wright, a famous horror film actress known as a "scream queen," greets her with icy disdain. Rosie is shocked and overjoyed, confirming she did not send the invitation. Aunt Grace, Constance's warmer sister and Vesper's surrogate mother, welcomes her with affection. During the dinner blessing, the congregation chants "Hail Satan," revealing the family's faith. Vesper mutters along sarcastically, nauseated by the rituals she rejected years ago.
That evening, Rosie tells Vesper she does not know who sent the invitation and apologizes for marrying Brody, saying the relationship developed naturally after Vesper left. Later, Brody sneaks to the house, kisses Vesper, and confesses he still has feelings for her. Vesper asks about her father, whom she has spent years trying to find, but Constance has always refused to reveal his identity. Back in her childhood bedroom, Vesper finds unsettling signs of intrusion: A window she cannot open stands wide open, and a photograph of her father's hand on her childhood shoulder has been placed on her pillow.
On the wedding day, Vesper dons a tight red satin dress she bought out of spite and descends through a hidden passageway beneath the barn into the Hell's Gate House of Worship, an underground cathedral adorned with stained glass depicting hellfire and statues of Baphomet, a horned goat-headed figure central to the sect. The ceremony includes a lamb sacrifice: Rosie holds the animal while Brody slits its throat. Vesper looks away and plugs her ears. The couple is pronounced husband and wife while Vesper sits alone beside the pooling blood.
At the reception, the congregation falls to their knees, screaming and chanting. A man in a dark suit appears on the dance floor. Vesper recognizes him: her father, whom she has not seen in fourteen years. He greets the crowd as their Lord and announces he has come for his daughter. Outside, he tells Vesper his name is Lucifer and that he is Satan, King of Hell. He claims Vesper is "the harbinger of the apocalypse," that her very existence validates the faith she denies. Constance kept his identity secret, intending for Vesper to learn the truth at her confirmation ceremony at eighteen, but Vesper left before then. Vesper is incredulous but cannot resist her father's pull. During a dance, he insists the world is ready to burn and she is "the match."
Overwhelmed, Vesper tries to leave. Rosie blocks her path on the porch; desperate to get past, Vesper reveals she kissed Brody the night before. Constance intervenes, telling Rosie to let Vesper go. Walking Vesper to the driveway, Constance says flatly, "I never wanted you. And, ironically, I could never act like I did" (155). Vesper catches the last train home and tears off her pentagram necklace at Penn Station.
Back in Westchester, Vesper is rehired at Shortee's by George, the new manager, and they begin dating. After they sleep together, George finds the pentagram necklace in her nightstand, though Vesper is certain she threw it away. She tells him she was raised in a Satanic cult, the first time she has told anyone, and George reacts with empathy. But he shares her secret with her coworker and friend Kerri in a misguided attempt to defend Vesper. Kerri confronts Vesper in the bathroom, mocking her. Mid-argument, Kerri slips on the wet floor and smashes her teeth on the counter. Vesper is horrified but notices part of her feels nothing. Storming through the kitchen, she thinks she hopes the place burns, and flames erupt from the stove.
Alone at a bar, Vesper revisits her worst memory: as a teenager, a man broke into her home to kill her, but when she told him to stop, he fled in terror and died falling down the stairs. She now realizes he was a former Hell's Gate member who wielded a crucifix, not a knife, believing she was evil. Lucifer appears, confirms the violent incidents around Vesper are manifestations of her supernatural power, and goads her into breaking George's hands with her mind. Stunned and defenseless, Vesper surrenders and lets her father drive her back to the farm.
At home, Grace gives Vesper pills that knock her unconscious. She wakes as Rosie dresses her in a crimson gown covered in beaded pentagrams. A sharp pain pulses at her side. Lucifer presides over a feast, declaring this the "last meal before the reign of hell." He reveals that Vesper is "the Lamb" who must "open the seal," a ritual possible only once every six years and only through her.
In the cathedral, Lucifer produces a bone: Vesper's rib, surgically removed while she was drugged. Vesper tears open her dress and finds bloody stitches at her side, realizing that what her father ate at dinner was her own flesh. She falls at Constance's feet, begging her mother to intervene, but Constance turns away. Lucifer drags Vesper to a stone basin and slits her throat. Her blood pours out, the cathedral goes dark, and she dies.
Then she wakes, on fire but unharmed. Behind her gapes a volcanic sinkhole: the opened seal to hell. Her throat has healed, and she can conjure and extinguish fire at will. Lucifer urges her to release the legions of hell, but Vesper directs her flames into the pit, choosing hope over bitterness. The cathedral collapses around them. Grace, Brody, Rosie, and the rest of the congregation slide into the chasm. Constance, the last to fall, walks calmly to the edge, hands Vesper the skull hairpin from the
Death Ransom franchise, and whispers, "Draw blood" (266). Then she falls. Vesper stabs her palm with the hairpin and lets her blood drip into the void. The seal folds shut, Lucifer vanishes, and the pit becomes dirt. Vesper crawls out as the barn burns behind her, finds a lamb on the grass, and carries it into the night.
In an epilogue set years later, Vesper lives under a new name, disguised by a blond bob. She returns to the farm, now a horror-themed museum, for a screening of a biopic about Constance. At a memorial stone, she incinerates the photograph of her father's hand in her palm, leaves the pentagram necklace, and places the skull hairpin at the foot of the stone. She hears what she believes is her mother's voice whispering, "Go now. Don't look back" (289). A faint smell of sulfur reaches her, but Vesper turns toward the road, resolving that this time she will not look back.