1859 Back in England after surviving the horrors of Cawnpore, John Williamson travels to London in search of a friend from his former life. But the man he is looking for is caught in a web of criminality centred on the notorious slum of Seven Dials. The intelligence services are seeking his friend too, convinced that there is espionage as well as criminality afoot. Blackmailed into spying on his friend, can Williamson save the man he loves from certain death without dying himself. And where does Karl Marx fit into all this?