"London contains many mysteries of crime," he said to himself as he alighted at the station and strolled home. "And here is one, I feel sure. Boyne is playing some clever game. Perhaps he seeks to inherit property belonging to the person whom he holds in captivity, and whose death may indeed have been registered!" Such a case—and more than one—was on record. Cases of people presumed by the law to be dead, yet they were still alive, held in confinement by those who benefited by their money. Durrant, who had read deeply of the mysteries of crime, recollected the case of Mrs. Marvin, of Hounslow; of George Charles Pepper, of Richmond; or Doctor Heaton, of Curzon Street; the celebrated case of the sisters Tredgold, and others, all of whom were concerned in the holding in bondage of those whose fortunes they secured. His inclination led him to go direct to Scotland Yard, and reveal what he had heard and seen, but Marigold had urged him to refrain from doing so until they had investigated further. She held Mr. Boyne in such high esteem, and her aunt held such a comfortable post, that she was most reluctant to put any suspicions before the police. It was in accordance with the girl’s wishes that he did not go straight to the Criminal Investigation Department. Yet he knew too well that the police, who discover so many "mare’s nests" daily, are slow to move until a tragedy occurs. And then it is often too late, for the perpetrators of the crime have vanished, either abroad, or into one or other of the criminal bolt-holes which are ever open to those who know. The public never realise that in the great underworld of London there are people who make a living—and a very good one, too—by successfully concealing for weeks, months, nay, years, those for whom the emissaries of Scotland Yard are in search. The clever criminal knows of these burrows where he can live quite cosily, and surrounded by comforts, defying all police inquiries until the hue and cry has died down, and then as a stoker-fireman, or in some menial capacity, he gets abroad a free man—free to enjoy the proceeds of his crimes. At first Gerald Durrant had suspected Bernard Boyne to be one of those obliging persons who offer safe asylum to criminals, but the wearing of that ghostly cloak by the owner of the house dispelled any such theory. No. As he entered the house, after that exciting evening, he was firmly convinced that Boyne held somebody—man or woman—in captivity. And he intended, at all hazards, to learn the truth. *CHAPTER VIII* *ON LOCH LOMOND* A bright brilliant day on glorious Loch Lomond, which, with its wooded islands, is one of the most picturesque of all the Scottish lakes.