Inspector French’s change of plans was due to a new idea which suddenly, like the conventional bolt from the blue, flashed across the horizon of his vision.
For some reason he had been unable to sleep on that night on which he had completed his proof that the Whymper incident had been engineered by Roper. French, as a rule, was a sound sleeper: he was usually too tired on getting to bed to be anything else. But on the rare occasions when he remained wakeful he nearly always turned the circumstance to advantage by concentrating on the difficulty of the moment. His brain at such times seemed more active than normally, and more than one of his toughest problems had been solved during the hours of darkness. It was true that he frequently reached conclusions which in the sober light of day app
