One night, two teenage friends Dominique and Ursula wander a shadowed graveyard, drawn to a toppled tombstone where a flash of lightning reveals a pale, blank book tucked inside the soil. The book, as they soon discover, holds a sinister promise: it grants power to those who write in it, but at the cost of the writer’s soul. Ursula pockets the mysterious volume, convinced that fate dragged her to this dangerous find, while the world around them—bullied by a group of cheerleaders named Heather, Georgia, and Lisa—seems ready to grind them down.
The trouble begins almost at once. Ursula, emboldened by the find, whispers a cruel wish into the book, setting Heather’s world on edge as harm descends upon her. Heather’s legs are broken in two terrifying car incidents, a shocking “freak accident” that leaves the school community reeling. Despite the evidence, Heather’s friends and the townspeople remain wary, and Ursula’s grip on the book only tightens. The power to shape fate tempts the two girls to press further, while the consequences creep closer to those they care about most.
In the midst of fear and doubt, Ursula targets Heather’s boyfriend, Kyle, and a dangerous line is crossed: during a Chemistry class exam, a corrosive liquid burns and blistered his face after a fall, signaling that the book’s reach is broader and more personal than anyone anticipated. The pair’s dynamic grows darker as the book’s pages fill with an ominous Latin title—Ephemeris Diaboli—signaling that the relic is no ordinary tool but a doorway to something far older and more dangerous. Dominique, troubled by the chaos, urges Ursula to abandon the book and seek help, but Ursula’s hold on the power is hard to break.
As the danger escalates, Lisa overhears their confrontation, and the two girls dig deeper into the artifact’s history. Research reveals the book’s English alias, the Devil’s Diary, and its disturbing reputation: the kind of object that only seeks out the ambitious and corrupts those who dare to wield it. At Heather’s hospital bedside, Georgia and Lisa disclose what they know about Ursula and the book, heightening the sense that loyalty and betrayal are as lethal as any supernatural force.
Desperate for guidance, Dominique seeks counsel from a church minister, Father Mulligan, who warns that the ancient book is crafted by the Devil and can manifest the worst impulses in people. He advises that Ursula must be kept away from the relic, yet skepticism lingers about whether the book’s evil is truly real or just a chilling myth. Undeterred, Ursula presses on, drawing closer to darkness with every cruel act.
The book’s influence intensifies as its hold over Heather’s circle grows. Heather’s friends steal it back from Ursula, and a cruel chain of vengeance unfolds: Heather forces Georgia to write a cruel inscription that leads to Ursula’s teeth, hair, and vitality being erased by a brutal, deadly fate. Georgia herself betrays Heather, setting up a tragic accident that ends Heather’s life in a hospital. Georgia’s betrayal extends further when she manipulates Lisa into a fatal electrocution via a malfunctioning stage light.
Retaliation spirals as Dominique retrieves the book, tearing out pages and hurling them against a wall, watching Georgia strike her head and die from the impact. The toll of the book’s power weighs heavily on Dominique, who is soon beset by trauma: an unsettling sense of what she’s become and what she’s chosen to do in its name. When Dominique faces the darker parts of herself—culminating in a brutal moment with her sexually abusive stepfather—she writes again in the book, hoping for his demise.
The power-hungry Frank enters the story in a new, perilous way, and the consequences spiral even farther. Dominique brings the book to [Father Mulligan], who refuses to safely contain it, and another would-be collector, Father Sanchez, asserts a more dangerous hunger for the relic. His arrival ushers in a catastrophic confrontation in which the book consumes him in flames, as if the flames themselves were a manifestation of the demonized power contained within.
In the wake of these horrors, Dominique is left reeling, bound for a psychiatric hospital six weeks later as she contends with the memories and the weight of the book’s influence. A grim vision closes the tale: two boys uncover and lift the book from a graveyard resting place, a clear reminder that the cycle could begin again, trapping another soul in the same cycle of power, violence, and despair.
