When Christian Vellacott passed out of the drawing-room window in answer to what he naturally supposed to be a signal-whistle from Hilda or Sidney, he turned down the narrow, winding pathway that led to the moat. The extreme darkness, contrasting suddenly with the warm light of the room he had just left, caused him to walk slowly with outstretched hands. Floating cobwebs broke across his face, and frequently he stopped to brush the ............