Susan Hart (born Caitlin Swift) is the daughter of American shipping magnate Theodore P. Swift. After marrying a secret husband (Matthew Judge), Swift and Judge flee to Whitechapel, London, under the assumed names "Long" Susan Hart and Captain Homer Jackson. During these years, she serves as madam of her own brothel at a building on Tenter Street owned by Silas Duggan. It is in this capacity that Hart makes the acquaintance of prostitutes Rose Erskine, Bella and Charity, as well as the police officers of H Division.
Following the murder of Silas Duggan, Hart acquires Duggan's property assets in Obsidian Estates as a means to expand and legitimize her own business ambitions.