Hilda and her family became low on money to the point that all of their house's furniture is removed from the house. On Buck's birthday, he wishes that he and his family have a home with furniture, and at that moment, the family discover that they have inherited the house of Cyrus's late uncle, Dr. Plato Zorba. Hilda and her family quickly moved into the mansion, which includes Dr. Zorba's eerie servant, Elaine Zacharides. However, Hilda and her family soon discover that the house is also haunted by twelve vicious ghosts.
One night, Elaine convinces Cyrus, Hilda and Medea to join her and have a seance. During the seance, Plato's ghost temporarily possesses Cyrus, and through him, uses cryptic messages to try and warn the family that the other eleven ghosts will try to make one of them the thirteenth ghost. However, Hilda and the family fail to crack the code.
The day after Ben Rush was killed trying to silence Buck from revealing the house's hidden fortune, Hilda and the family discover the money, and consider using it to move to another house.