For their one-year anniversary, Malcolm, a doctor, takes his girlfriend, Liz Tatiana Maslany, a painter, on a weekend trip to a secluded cabin in the countryside. Upon arrival, Liz discovers a boxed cake tucked inside the cabin, and Malcolm explains that it’s a gift from the caretaker. At dinner, their evening is interrupted by the unexpected presence of Malcolm’s obnoxious cousin, Darren Birkett Turton, and Darren’s European model girlfriend, Minka Gina Vultaggio, who supposedly doesn’t speak any English. As Malcolm scolds Darren, Minka in English warns Liz that the cake tastes awful, though Liz later devours a slice at Malcolm’s urging, brushing off the warning.
Soon, Liz is haunted by unsettling visions: screams, blood, and a pregnant woman who bears an eerie resemblance to her. In the middle of the night, she feels compelled to the cake and consumes an entire slice, even after discovering severed, bloodied fingers concealed inside. The next morning, Minka is attacked by an unseen force while walking in the woods, setting a disturbing tone for what follows.
Malcolm says he must return to the city to care for a patient but promises to be back that evening. While alone, Liz reaches out to her friend Maggie Tess Degenstein, who suggests Malcolm might be unfaithful, a theory that only fuels Liz’s anxiety. Strange creatures begin to emerge in the house, and Liz encounters the ghostly figure of Minka along with a woman wearing a plastic bag over her head. Darren arrives again, insisting on entry, and Liz hides in the bathroom as he retrieves a meat cleaver and roams the house before being killed by unseen forces. Desperate, Liz calls Maggie again to come get her, but the poor cellphone signal leaves her isolated.
When Malcolm returns, Liz begs to go home, though he manages to calm her and coaxes her to share a drink before they depart. As the night wears on, Liz grows more suspicious of Malcolm’s behavior. She locks herself in the bathroom and discovers an old photograph of Malcolm with a wife and daughters that suggests a hidden life. Malcolm appears, claiming the lock is useless, and Liz confronts him about the alleged infidelity. He then reveals a chilling history: two centuries ago, as teenagers, he and Darren encountered a pregnant trespasser on their property, shot her in the leg, and locked her in a pigpen. She gave birth to the strange creatures now haunting Liz. The two men have spent 200 years luring women to feed to these creatures, who have granted them longer lifespans in exchange; the screaming women Liz has seen are their past victims. He also confirms the cake was drugged to knock her out.
Malcolm locks Liz in the basement, where she is surrounded by the spirits, including the bag-headed woman who lifts her bag to reveal a face with multiple eyes, noses, and mouths. Rather than attacking, the creatures seem to embrace Liz because of her resemblance to their mother, whose disembodied head—kept in a jar of honey—they have preserved. Liz experiences a perverse mix of laughter and horror as the beings close in around her. Meanwhile, Malcolm begins to age rapidly and is attacked by one of the creatures, a fate that seems to mirror his own grim pact with them.
The following morning, an old, upside-down Malcolm finds himself hanging from a tree. Liz, now with the creatures’ black, inky eyes, approaches him and forces him to drink more of the drugged cake. He pleads for release and proclaims his love, but Liz coldly accuses him of lying, ending with a ruthless act: she dunks his head into a jar of honey and walks away, leaving him to his fate as the house settles into a chilling silence and the forest around them seems to close in.
