The Golden Bat by Fred M. White — Read

Ray was not as much disturbed over this unexpected happening as he might have been, because he had more than a shrewd suspicion that no particular harm would come to Angela. That, he felt, was no part of Keen's programme. For some reason or another, the man in question was really fond of the girl, which was certainly to his credit, otherwise he would never have saddled himself with the cost of her education and maintenance, which must have been a considerable item. It was just possible that Keen might have had some sort of affection for Angela's mother; but, be that as it might, Angela had in some way touched that black heart of his, or she would never have remained all these years under his roof.

It was possible, on the other hand, that Angela was more or less a pawn in the great game that Keen was playing. Doubtless, he had smuggled her out of the way, most probably because she had been detected in some acts of espionage at a critical moment, and therefore had to be removed to some secluded spot where she was powerless from further harm until some new and startling robbery had been successfully accomplished. Nor would this be difficult to a man of Keen's infinite resource. He could make up some ingenious story in connection with Angela's parentage, and if this was plausible enough he would be ready to follow it up if it took her to the extreme end of the country. The idea that the girl had been kidnapped in London was just the sort of thing to occur to a man of Keen's subtle nature, and perhaps something had happened whereby it became necessary to throw dust in the eyes of the female servants in the flat, none of whom would have the slightest idea of what sort of life their master was leading.