The narrative unfolds in Oxnard, California in June 2012, as recent high school graduate Jesse (Andrew Jacobs) throws a celebratory party for his graduation with family and friends, including his father, sister, and grandmother. During the festivities, Jesse shares with his friend Marisol (Gabrielle Walsh) his suspicions about their peculiar downstairs neighbor, Ana (Gloria Sandoval). He describes how the group often hears eerie wails and moans seeping through the ventilation shaft that connects their apartments to Ana’s.
The following day, Jesse, accompanied by his friend Hector (Jorge Diaz), starts filming some amusing antics with his new GoPro camera. However, the mood shifts when they notice Oscar (Carlos Pratts), a former classmate, leaving Ana's apartment after a strange commotion. When they attempt to engage with him, Oscar acts suspiciously before making a hasty exit. Intrigued by the ongoing mystery, Hector persuades Jesse to investigate further by lowering the camera into Ana's unit. To their shock, they behold Ana and a young woman, both unclothed, with Ana inscribing unusual symbols on the woman's belly. The two quickly retreat when Ana seems to catch on to their spying.
Later, their friend Marisol proposes a chilling theory that Ana may be a "bruja" or Mexican witch. As Jesse and Hector plan to sneak into Ana's space, they come face-to-face with an angry woman who shoves them out just as Ana arrives home. That night, while trying to set off some fireworks, the boys are startled when Oscar suddenly appears and darts back inside Ana's apartment. Shortly after, the police arrive to discover Ana’s brutal murder, leading them to believe Oscar is the perpetrator.
Although still on the loose, the fear of Oscar’s gang member brother, Arturo (Richard Cabral), keeps Jesse and Hector from reporting anything. Their curiosity drives them to Ana's apartment, where they uncover a bloodied scene filled with occult artifacts and a VHS tape that reads "Katie & Kristi 1988." Upon their departure, they are confronted by Arturo, who insists that Oscar is innocent and warns them to stay away. Before they leave, they manage to swipe one of Ana’s journals.
The following morning, Jesse discovers a mysterious bite mark on his arm, accompanied by an unsettling change in his family dog Chavo, who grows fearful of him. As they delve into the journal, they find disturbing illustrations echoing their previous discoveries. One passage appears to outline a way to open gateways to ominous locations. That evening, while consuming tequila, the friends experiment with a Ghost Box—a device believed to communicate with spirits. To their horror, the device responds affirmatively to Jesse's inquiries, affirming a spectral presence lurking amongst them. Despite Jesse’s grandmother's disapproval, the dark game continues.
As supernatural events intensify, Jesse begins to exhibit extraordinary physical prowess, saving himself and Hector from thugs during a mugging. They later show the recorded incident to Marisol, leaving them puzzled about Jesse's sudden strength. Following another Ghost Box session, they receive cryptic confirmations regarding a protective presence. Jesse's strange abilities evolve, enabling him to perform gravity-defying stunts, which he showcases during a chaotic encounter at a block party with two girls, Penelope (Catherine Toribio) and Natalia (Gigi Feshold). He sneaks Penelope into Ana's apartment, where they make a shocking discovery—a trapdoor leading to a basement. After a brief scare, Jesse encounters Oscar, who reveals they both bear bite marks and suggests that they might have to end their own lives to prevent harming their loved ones. Following this disturbing conversation, Oscar leaps to his death.
With growing unease, Jesse, Hector, and Marisol probe deeper, discovering an altar in the basement complete with photos that eerily connect Jesse to Oscar and the missing children. The dark path continues as Jesse's behavior deteriorates, marked by violent outbursts and increasing physical strength. Their investigation leads them to Ali Rey (Molly Ephraim), a survivor with knowledge of the malevolent forces at play. She warns the trio of the coven named “Midwives,” who prey on firstborns, marking them for sinister purposes.
The tension escalates when Jesse begins exhibiting traits of possession. A desperate attempt by his grandmother using traditional methods only leads to further horror as Jesse exhibits terrifying powers, turning the atmosphere fraught with dread. As realities intertwine, Jesse's friends witness the horrifying implications of their curiosity, witnessing each other's downfalls amidst ancient rituals and demonic forces.
What follows is a frantic race against time, with Hector and Marisol confronting the depths of darkness that threaten to claim Jesse entirely. A climactic chase ensues, testing their resolve as they battle supernatural entities and possessed forms of those they once cherished.
Ultimately, the saga culminates in a heart-stopping confrontation with Jesse now fully entrenched in darkness, leaving Hector to navigate the remnants of their friendship as the lines between reality and the supernatural blur beyond recognition.
