“One moment,” I asked. “Did the stable-boy, when he ran out with the dog, leave the door unlocked behind him?”

“Excellent, Watson, excellent!” murmured my companion. “The importance of the point struck me so forcibly that I sent a special wire to Dartmoor yesterday to clear the matter up. The boy locked the door before he left it. The window, I may add, was not large enough for a man to get through.