In the small American town of Mill Valley, on Halloween night in 1968, a group of teenagers—Stella, Auggie, Chuck, and the drifter Ramón—stumble upon the eerie, abandoned mansion that once belonged to the wealthy Bellows family. The mansion harbors a dark past, shrouded in grim rumors about the family's tortured daughter, Sarah, who was said to have possessed a knack for telling ghastly horror stories. Ignited by curiosity and a love for the macabre, the teens embark on a dare that leads them to uncover a secret room in the mansion, where they discover a mysterious book filled with horrific tales.

As the night progresses, Stella, a young aspiring writer with a fascination for the supernatural, takes the book home, only to find that it is still being written by an invisible hand—Sarah's hand. The stories begin materializing in the real world, with each one centring on one of the teens, invoking their personal fears and nightmares. With every vengeful tale that writes itself on the pages, they realize that Sarah’s malevolent spirit is reaching out from beyond the grave, seeking to exact her spectral revenge. As the group desperately seeks a way to stop the tragic events from unfolding, they delve deeper into the Bellows family history, unraveling Sarah’s tortured life and the grim truth that is entwined with the destiny of their own town.