Nick returns to his parents' home for Christmas, eager to introduce his girlfriend, Annji, to his family, despite having a rather strained relationship with them. The gathering includes his pregnant sister, Kate, her husband Scott, and their grandfather, Grandad. Tensions escalate when both Kate and Grandad make derogatory remarks towards Annji, who hails from Indian descent.
As they try to navigate the awkward family dynamics, a mysterious black substance envelops the house, trapping them inside. They soon receive ominous messages indicating that their food is contaminated and urging them to cleanse themselves with bleach and take vaccines that mysteriously drop down the chimney. Although the syringes appear reused, Tony, Nick’s father, insists everyone should comply. Chaos reigns when Grandad suddenly dies after vomiting a black liquid, heightening the sense of dread.
The situation worsens when messages on the television accuse one of them of being infected. The family turns against Annji, suspecting her, and locks her away with Grandad's lifeless body, all against Nick's vehement objections. As tensions boil, Nick attempts to escape, but the television broadcasts his plans, leading to a violent confrontation. In the frenzy, Kate is harmed, and the situation takes a darker turn when it’s revealed that the television is in control, mandating that they extract information from Nick, whom they now see as a spy.
With rising stakes, Nick manages to get Annji downstairs, but tragedy strikes again when Beth, desperately trying to help, succumbs to the enigmatic black smoke. In a desperate moment, Nick disrupts the television's broadcast, only for the house to violently shake as it claims to be "resurrecting." Captured and restrained, Nick and Annji learn the horrifying demand that Tony and Scott must sacrifice them. A brutal struggle ensues, resulting in Scott's death at the hands of Tony, who then turns his aggression on Nick.
In a climactic fight, Nick defeats Tony by shattering the television, only for it to manipulate Tony's corpse through an intertwined network of living black wires. As chaos reigns, even the defeated wires begin to pulsate with a life of their own. In a tragic twist, Tony, now a puppet of the wires, claims Nick and Annji, while the horrifying sight of their friend Kate being reduced to bones becomes a chilling reminder of their predicament. Tony brings in a new television that exploits the newborn baby, renaming her "Ruby," and begins its sinister broadcast that commands worship. Outside, the view shifts to show that every home is enveloped in the same creeping black wires, hinting at a far-reaching curse that binds them all.
