Susan was one of the six women who gave birth to baby girls on June 6, 1994, beginning a prophecy that stated that one of them would become the "Devil's Hand," an emissary of Satan, on her 18th birthday. One of the girls is killed by her mother after birth, leaving Susan's daughter, Mary, as one of the five remaining girls
Nearly 18 years to the day later, Susan returned to the community under a hidden cloak and killed each of the four other girls, as well as Mary's evil stepmother, Rebekah. Mary had believed her mother to be deceased until her father, Jacob Brown, told her the truth. Afterwards, Susan reunited with Mary, who was driven there by Trevor, and Susan gave the impression that Elder Beacon, a religious fanatic, was the one killing the girls. Susan sees Mary again minutes before midnight on her 18th birthday and confesses everything; stating that she killed the other girls to change the demonic prophecy and making sure that Mary becomes the Devil's Hand and lives at full strength
Susan tells Mary that at midnight the devil will take possession of Mary’s soul, she’ll become one of his soldiers, becoming unimaginably powerful