In the year 1906, one of the most enigmatic and terrifying mansions in the United States rises amidst a desolate landscape. The story follows Sarah Winchester, the fervent heiress of the fortune from the famous arms company, who is obsessed with the spirits of those who have suffered because of her legacy. After the tragic death of her husband and child, Sarah becomes convinced that her family is being haunted by supernatural forces. To appease these ghosts, she begins constructing a gigantic mansion, a continually expanding work that defies all architectural logic, featuring endless rooms, staircases that lead nowhere, and doors that open to emptiness.
A psychic doctor, Dr. Eric Price, is called in to assess Sarah's mental health, as everyone believes she has lost her sanity due to her obsessive building. As Price investigates the mansion, he realizes that the house has a life of its own and that the spirits, both from Sarah's past and others who remain trapped, seem to have their own agenda. Caught between reality and supernatural manifestations, the doctor uncovers dark and chilling secrets that lead him to question not only Sarah's sanity but also his own perception of death and the afterlife. The horror and anguish drive him to fight for both his life and Sarah's before the ghosts take control.