Edmund and Dorothy Yates are a middle-aged couple with a dark past. Years earlier, they were committed to a mental institution for committing a series of cannibalistic murders. Deemed rehabilitated, they are released into the care of their daughter, Jackie, who is fully aware of their history. However, Jackie has kept this family secret from her younger sister Debbie, who knows nothing of their parent's past. The Yates try to reintegrate into society while residing in a farmhouse in the English countryside, but deep-rooted issues hover beneath the surface, threatening to disturb the fragile peace.

Jackie, burdened with the responsibility of monitoring her parents, leads a stressful double life, trying to maintain normalcy and protect her sister. Meanwhile, Dorothy's old impulses begin to resurface, prompting a series of eerie events in the surrounding community. Jackie's fears escalate as she suspects her mother is reverting to her old ways. As the tension builds, Debbie's curiosity leads her to probe into the past, putting her in grave danger as she edges closer to the truth. In the shadows, the quaint rural setting morphs into a backdrop for a nightmarish relapse of horror, with the family's struggle against their nature becoming increasingly desperate.