"With no definite destination in mind Duff wandered along down Piccadilly. It was a thoroughfare of memories for him and now they crowded about him. Up to a short time ago he had been divisional detective-inspector at the Vine Street station and so in charge of the C.I.D. in this fashionable quarter. The West End had been his hunting preserve. There looming in dignified splendor through the rain was the exclusive club where with a few quiet words he had taken an absconding banker. A darkened shop front recalled that early morning when he had bent over the French woman murdered among her Paris gowns. The white facade of the Berkeley brought memories of a cruel blackmailer seized dazed and helpless as he stepped from his bath. A few feet up Half Moon Street before the tube station Duff had whispered a word into a swarthy man's ear and seen his face go white. The debonair killer wanted so badly by the New York police had been at breakfast in his comfortable quarters at the Albany when Duff laid a hand on his shoulder. In Prince's restaurant across the way the inspector had dined every night for two weeks keeping a careful eye upon a man who thought that evening clothes concealed successfully the sordid secret in his heart. And here in Piccadilly Circus to which he had now come he had fought one memorable midnight a duel to the death with the diamond robbers of Hatton Gard."