Rena remarried a man with two children, and one month has passed since she moved into their household. Though the siblings appear warm and welcoming on the surface, they have secretly developed an intimate relationship with each other. Devoted to their late mother and deeply protective of their father's memory, they fear Rena has replaced her and now threatens their family bond. Convinced she doesn't belong, they conspire to torment her relentlessly, driving her out of the house through escalating acts of psychological and sexual abuse. As their sinister motives unfold, the dark secrets binding the siblings come to light.