Back from his adventures in the Far East, John Williamson intends to retire and live quietly in his home town in Devon. But first he heads to London to see the glamorous capital of an Empire on which the sun never sets, and looks up a childhood friend. Yet the friend has fallen into bad company and now lives in the notorious lawless slum around Seven Dials. The police Special Branch are convinced that criminality in the Seven Dials has links to foreign subversives. Is Williamson's friend in league with the French or is he working for Karl Marx's Communists? When Williamson is blackmailed into helping the police, he finds himself trapped in a world of crime and intrigue which shows him another side of London.
