In a snowy New Mexico town during the early 1980s, a lonely and bullied 12-year-old boy named Owen spends his nights peering out onto the courtyard of his dreary apartment complex and his days fantasizing about revenge against his tormentors. His life takes an extraordinary turn when a mysterious girl named Abby moves in next door with an older man, who is presumed to be her father. Despite her initial peculiarity and cryptic warning that they cannot be friends, Owen is drawn to Abby, finding in her a kindred spirit who similarly bears the weight of loneliness and social isolation.

As their bond deepens, a series of brutal murders begins to rock their small town. Meanwhile, Owen becomes increasingly suspicious of Abby's odd habits and nocturnal lifestyle. Unbeknownst to him, Abby harbors a dark secret that explains her aversion to daylight and need for barefoot ventures into the night. The connection between these events, and Abby's true nature, begins to emerge as Owen confronts the reality of life beyond childhood innocence, and the pair navigates the complexities of trust, companionship, and otherworldly revelations.