It is 1863, and London's East End is the soot-covered hub of the greatest Empire the world has ever seen. Steamships cleave the oceans, and airships crisscross the skies. Fortunes are to be made, but not all are enriched.

In their struggle to survive, the Preston sisters could not have been more different. Molly the Lubber (a factory girl) lives with her mother; Dolly the Wagtail (one of the great city's unfortunates) is an attraction at a famous bawdy house; and Polly the Mollisher (a criminal's bedpartner) runs the Golden Bell public house, a hotbed of crime.

Molly is flattered when Mr. Lewellen, a handsome young draughtsman at the factory where she works, takes to escorting her home after her shift. The streets between Whitechapel and the London Docks are not for the faint-hearted. One morning arriving at work, Molly makes a horrifying discovery which sets into motion a series of events that may have international repercussions, and will either bring the sisters together, or see them killed.