Five years after her husband died in a tragic car accident, Linda began rebuilding her life and remarried her late husband's business partner Greg. When her daughter Scarlett returned home from college, she noticed that her new stepfather was behaving strangely and suspected that he might be having an affair. She followed him, and when he met another woman, it seemed to confirm her suspicion. However, when the same mysterious woman was reported dead in the news reports a day later, the situation became even more terrifying. Scarlett began to doubt - who was the person living in their house?