The woman in question is named Sarah, and she lives a quiet life in her beautiful countryside home. She's still recovering from the emotional trauma of her divorce from her husband Tom, who cheated on her with one of her best friends. One day, Tom unexpectedly shows up at her doorstep, claiming that he wants to buy the house from her as a country getaway for him and his new girlfriend.
Sarah is initially polite but cautious around Tom, and entertains the idea of selling the house to him. However, as they tour the house together, Tom begins to revert to his old manipulative ways, attempting to guilt-trip her into selling him the house by making her doubt her own financial situation and abilities as a homeowner. Eventually, his true intentions become clear: he wants to tear the house down and build a luxury resort on the land.
At this point, Sarah's anger and bitterness towards Tom boil over, and she knocks him unconscious before locking him in a cage in the cellar. She becomes obsessed with keeping him there, feeding him only scraps and refusing to let him out until he admits to his infidelity and apologizes for his past actions. Over time, Tom begins to suffer both physically and mentally, and Sarah starts to lose her grip on reality as she becomes more and more fixated on her act of revenge.
Meanwhile, Sarah's sister and a close friend begin to suspect that something is wrong and start investigating her strange behavior. Eventually, they discover Tom locked in the cellar, and Sarah is arrested for kidnapping and assault. The film ends with Sarah serving time in prison, as she reflects on the satisfaction she felt from finally getting revenge on Tom for his betrayal.
