The final season finds its end during the cold winter of 1901, taking the heroes to a place where a dark secret they all share emerges to destroy the lives they've built.

Inspector Edmund Reid travels deep into the seedy criminal London underworld hell-bent on taking back the blood-stained streets of Whitechapel. But Reid isn't fighting this battle alone. He's joined by Detective Inspector Bennet Drake, a hard man who prefers to let his fists do the talking, Captain Homer Jackson, a brash American with a voracious appetite for vice, and Long Susan, a madam with shady secrets.

Three years have passed since the Leman Street locomotive disaster, when DI Edmund Reid is forced to return to Whitechapel to help clear his former associate's name. Once again Reid finds himself, along with DS Drake, plunged into a criminal underworld that threatens to overtake London's East End on the eve of Queen Victoria's diamond jubilee celebration.