Susan Carter is the matriarch of a family who moved into a new house haunted by a "ghost."
With her family, Susan moved to Stratton, Nebraska after the death of her son Andy, attempting to make a fresh start. They had no idea of the history of the house and its previous owner, and arrived there with their moving van in tow to find Sam and Dean already in the house investigating the mysterious death of Bill Gibson.
The Carters came under attack by what the Winchesters initially believed was a ghost, but learned from reading the diary of Bill's deceased daughter, Rebecca, that the culprit was actually the girl that was the product of Bill's rape of Rebecca. Bill had locked the girl away to live inside the walls and basement of the house for her entire life. When the girl abducted Susan's young son, Danny, and Dean rescued him, he encountered a second child, the girl's brother, and ultimately shot him. Susan's husband, Brian, was forced to kill the girl when she attacked Susan and their daughter, Kate.
When the ordeal was over, a shaken Susan thanked the brothers for their help.