1895: London's scared. A killer haunts the city streets.

The pooor are hungry; crime bosses are taking control; the police force is stretched to breaking point.

While the rich rely on Sherlock Holmes, the celebrated detective rarely visits the densely populated streets of South London, where the crimes are sleezier and the people are poorer.

In a dark corner of Southwark, victims turn to a man who despises Holmes, his wealthy clientele and his showy forensic approach to crime: Arrowood - self-taught psychologist, occasional drunkard and private investigator.

When a man mysteriously disappears and Arrowood's best lead is viciouisly stabbed before him, he and his sidekick Barnett face their toighest quest yet: to capture the head of the most notorious gang in London...