Born and raised in Westminster, Mildred and Lilla had a youth of luxury and wealth. Their parents attempted to raise them as proper ladies, despite the signs that neither of their daughters seemed intent on cooperating.
After the death of her parents, Mildred started squandering her inheritance. She was soon forced to relocate to Lambeth, where she took a job at the local cemetery. Being a member of the Blighters, the street gang of which her sister had become one of the leaders, Mildred buried victims of her sister's crimes without a certificate of death, garnering the attention of the Metropolitan Police Service.
In 1868, Mildred was abducted by Jacob and Evie Frye, two Assassins hoping to diminish the Blighters' control over London. Despite Mildred's protests that Lilla was the one they were after, she was lead to Sergeant Frederick Abberline, an ally of the Frye twins, and imprisoned.