Bill Gibson was eating and watching television when the electricity in his home suddenly went out. He rose to investigate, but the door to the room was locked and wouldn't open. He turned see a wild-looking girl that he obviously recognized emerging from the closet toward him, and demanded that she stay away. The girl smiled, then raised a knife and killed him.
Sam and Dean followed the reports of the killing to Stratton, Nebraska, and searched the then empty house for clues. The Carter family arrived with a moving van as they searched, ready to make it their new home. They pretended to be from county code enforcement agents and sent them to a hotel behind the pretense of finding asbestos and a gas leak. They soon returned, however, and moved in after Susan Carter’s brother Ted declared that house was clean.
The girl found a kindred spirit in young Danny Carter, who had no fear of her and even encouraged her to play a game of catch with him. After his parents accused him of scrawling ‘’GO’’ in red crayon on the dining room wall, he protested that it wasn’t him, but the girl in the walls that did it, and she’d also told him that only he could stay in the house; the grown-ups had to leave, or else.
While the Carters were away, Sam and Dean learned from the housekeeper that found Bill Gibson’s body that his wife had died giving birth to their daughter, Rebecca, and that Rebecca committed suicide in their attic twenty years later. When they returned to the house believing there was probably something in the attic binding one of the Gibson women to the house, they found the family in a panic over Kate Carter’s encounter with a ‘’pervy ghost’’ and Danny’s insistence that there was a girl in the walls.
Unable to leave because everyone’s tires were slashed, Dean had gathered the family inside a salt circle for protection when the girl emerged from the shadows and stepped over the salt line. She lunged at Dean and a struggle ensued. Her attack was thwarted when Sam appeared and shined a flashlight directly into her eyes.
Sam found Rebecca Gibson’s diary in the attic and learned that her father Bill raped her and got her pregnant. He then locked the child away inside the house. The boys figured that the girl finally managed to break out and then killed Bill. Living in the bowels of the house her whole life explained her demeanor, and her acute sensitivity to light.
At one point, Danny disappeared and the search for him led Dean and Ted into the walls. Ted waited while Dean descended further into the basement where he found evidence that the girl had been surviving by eating vermin. Meanwhile, the girl sneaked up behind Ted and stabbed him through the neck. Dean carried Ted’s body out and when he returned, he found Danny bound and gagged. As he untied him, Danny warned that the girl had a brother, and that he was coming back. He immediately did and after a struggle, Dean shot him.
The girl attacked Susan and Kate where they hid outside, and Brian Carter killed her to protect them. After the case, Dean says he feels pity - and empathy - for the children who were turned murderous by a life of torture.
- IMDb lists the girl's name as "Lizzie Gibson".