“Let us reconstruct, Watson,” said Holmes after half an hour of silence. “I am not aware that in all our joint researches we have ever had a case which was more difficult to get at. Every fresh advance which we make only reveals a fresh ridge beyond. And yet we have surely made some appreciable progress.
“The effect of our inquiries at Woolwich has in the main been against young Cadogan West; but the indications at the window would lend themselves to a more favourable hypothesis. Let us suppose, for example, that he had been approached by some foreign agent. It might have been done under such pledges as would have prevented him from speaking of it, and yet would have affected his thoughts in the direction indicated by his remarks to his fiancee. Very good. We will now suppose that as he w
