Laura Woodson is a popular student known for her extensive online network of 800 Facebook friends. She shares an apartment with her friends Olivia Mathison, Isabelle, and her boyfriend Gustavo Garcia. Among her close companions are Kobe, her trustworthy confidant, and Tyler McCormick, the guy she admires from afar. However, the peace of their social circle is shattered when Laura receives a friend request from classmate Marina Mills, whose negative online persona raises red flags. Despite her better judgment, Laura accepts the request, leading to an unexpected friendship. Yet, Marina's increasingly obsessive behavior quickly begins to unnerve Laura.
Things take a darker turn as Marina requests to join Laura's upcoming birthday celebration. To avoid confrontation, Laura concocts a story that it will be a private affair with just her and Tyler. The truth comes to light when Marina stumbles upon a Facebook post that reveals the actual guest list, resulting in a fierce argument that uncovers an embarrassing truth about Marina's hair-pulling disorder. In a moment of distress, Laura decides to unfriend Marina, believing she has finally cut ties with the toxic relationship.
Tragedy strikes when Laura learns of Marina's suicide, sending panic rippling through their campus. Overwhelmed by guilt, Laura struggles to move on until a haunting video appears on her Facebook page. In it, Marina demonstrates her demise and depicts a chilling sketch of Laura in flames, leaving Laura feeling powerless as Marina's sinister influence lingers. Soon after, Gustavo is also targeted by Marina's ghostly spirit, leading to more torment.
In a desperate attempt to help him, Isabelle finds Gustavo in dire straits and takes him to the hospital, only for another disturbing video of him to surface on Laura’s social media, deepening her plight. Determined to get to the bottom of these mounting horrors, Laura and Kobe sneak into Marina's dormitory and discover a photograph that hints at her traumatic childhood in an abandoned orphanage. This revelation compels Laura to delve deeper into Marina’s past.
Visiting the orphanage reveals Marina’s true identity - Nedifar - alongside the dark history that has haunted her for years. The horrific fate of Marina’s childhood abusers, killed by black wasps, looms ominously as Laura connects the dots to Gustavo's downfall. Kobe's research into the dark legends surrounding black mirrors, which were once tools for witches, uncovers essential clues linking Marina’s tragic tale with the supernatural forces at play.
As the investigation progresses, the situation escalates when Isabelle falls victim to Marina's ghostly influence, resulting in more heartbreak for Laura. Olivia soon follows suit, overwhelmed by the same malevolent energy that claimed her friends’ lives. Fueled by sorrow and urgency, Laura and Kobe brave a daunting journey to locate the place where Marina met her tragic fate—a cursed spot tied to the sinister black mirror that catalyzed her transformation into an avenging spirit.
Kobe’s mental state deteriorates, and in a moment of panic, he betrays Laura, launching a frantic attack against her. After an intense escape, Laura learns that Marina ended her life in an abandoned factory near town—a crucial piece in unraveling this horrifying mystery. As Laura edges closer to answers, Tyler becomes yet another victim of Marina's wrath. The film reaches a chilling climax when Kobe succumbs to a swarm of vengeful wasps, further amplifying the horror that has enveloped their lives.
Ultimately, Laura confronts the ashen remains of Marina, only to be faced with a grotesque embodiment of her tormentor, a demonic figure not unlike Marina herself. As the conflict concludes, Laura emerges altered and draped in shadows, eerily similar to Marina, now gazing upon a new generation of potential victims with an unsettling intensity that forebodes the inevitable cycle of torment that awaits them.
