After a painful family dispute, Janet Slate leaves the home she shares with her older sister Lara and their single mother Maddie, relocating to apartment 1303 on the thirteenth floor of a downtown Detroit building. The move comes with a warning from a 9-year-old neighbor, Emily, who explains that a previous occupant of Janet’s new place killed herself—a detail that seeds unease from the start. Soon, strange occurrences begin to ripple through the apartment, and when Janet shows up at work with bruises, she pushes away coworkers’ concerns about possible abuse by her boyfriend Mark Taylor, insisting the marks come from sleepwalking rather than danger.
Janet’s world grows more unstable as the supernatural activity intensifies. Fearing for her safety, she opts to spend longer hours at the office rather than go back to apartment 1303. She reaches out to Lara to ask if she can return home, but Lara warns that Maddie is in the middle of another volatile “drunk psycho rant.” Janet asks about staying in a hotel, but the idea falls through because Lara cannot cover the expense. With Mark away, Janet contacts him to check in, and he agrees to help. Yet that same night, Janet is awakened by disturbing, otherworldly forces in the unit; Mark is not there to provide solace, and a chilling sequence follows—an invisible presence takes hold of Janet, driving her into a state of deepening depression that culminates in suicide. Lara arrives later to collect Janet’s belongings, only to encounter the same terrors that plagued her sister.
A detective who was assigned to the case eventually speaks with Lara, and she voices the growing belief that Janet’s death may not have been an isolated tragedy. The detective shares a broader pattern—mysterious suicides among tenants that have haunted the building for years. As Lara digs deeper, she uncovers the name of the first tenant from twenty years earlier: Jennifer Logan. The detective explains Jennifer’s harrowing backstory in stark terms: when she was twelve, she moved into apartment 1303 with her mother, Mary, a once-respected schoolteacher who had recently divorced. Jennifer’s life took a brutal turn when Mary lost her job during a tense conference, and Mary descended into a life of addiction and prostitution to keep a roof over their heads. The abuse Jennifer suffered escalated until she could endure no more, culminating in Jennifer killing Mary and burying her in a built-in closet. Neighbors soon complained of a putrid smell, drawing police and health inspectors to the scene. By the time they reached the apartment, Jennifer had already taken her own life; the decades that followed brought reports of other tenants who had died under suspicious circumstances, with Janet’s case standing as the most recent tragedy.
As Lara confronts the creeping terror, a grim warning from Janet—delivered in the form of a cryptic message while Lara bathes—tells her to leave the apartment and never return. Maddie’s insistence on staying or returning to the unit leads Lara to move back in, ignoring the warning. Jennifer’s presence manifests in terrifying ways, including the murder of Mark when she hurls him from a window. Lara, terrified and determined to escape, encounters Emily and the landlord, O’Neill, who finally reveals a painful truth: his daughter Emily, a victim of the same malevolent force, was the first to suffer after the building’s haunting began. Months after the initial haunting, a symbolic cleansing took place, and the building was reoccupied—only to become the site of more tragedies, including the earliest victims that Jennifer claimed once again as a warning to future tenants.
Lara learns that O’Neill, his daughter Emily, Janet, Maddie, Mark, and the other victims had all attempted to warn others about apartment 1303, but their warnings went unheeded. As Jennifer tightens her spectral grip, Lara grips a knife in a desperate bid to defend herself. Maddie, trying to reason with her daughter, pleads for sense and safety, but Jennifer—unmoved by such pleas—drives Maddie’s fate with a fatal push. Just as the danger closes in on Lara, the police arrive, and Jennifer vanishes, dissolving into the air of the apartment. Lara is arrested and booked for the murders of Maddie and Mark, left to face the consequences of a crime for which the true culprit remains unseen. As dawn breaks, Jennifer—the tormented spirit—reappears, seated in the same place where she once took her own life, a chilling reminder of the warning she and the building’s other victims tried to pass along: never move into apartment 1303.
