Bill Gibson was an incestuous widower from Stratton, Nebraska.
Dean Winchester was scanning the wires for cases when he came across a report of a man hacked to death inside a locked room, inside a locked house. As he and Sam Winchester were searching the house, which had been put on the market and was empty, the Carter family arrived, ready to move in. The boys pretended to be county code enforcers who had found asbestos in the house in an effort to keep the family away while they worked the case.
The Winchesters went to interview Bill Gibson's housekeeper, Mrs. Curry, who found his body. She told them that Bill was not an easy man to get along with, but added that she would have been bitter, too; his wife died giving birth to his daughter, and his daughter hanged herself in their attic twenty years later. She informed them that both women were cremated.
Sam and Dean returned to the house to find the Carters had come back and were being traumatized, and they determined that the culprit was a ghost. That was until a feral, knife-wielding girl breached their salt line. Sam searched the attic for clues and found the diary of Rebecca, Bill Gibson's daughter, and discovered that Bill had raped, impregnated and verbally abused his daughter, and kept their children locked away inside the house. Sam and Dean surmised that the girl broke out and killed Bill.
When the Carter's son Danny went missing, Dean went through the wall and into the basement in search of him. When he finally he found and unbound him, Danny warned him that the girl, whom he referred to as the girl in the walls, had a brother and that he was coming back soon. Very shortly thereafter, the boy attacked. Dean ended up shooting him in self-defense. Outside, the girl found Susan and Kate Carter in their hiding place and attacked them with a knife. Brian Carter killed her to protect them.