It was a long, lean Rolls-Royce, running smoothly with a gentle purring of the engine. Through the two vivid circles cast by the electric head- lights the waving grass fringes and clumps of heather streamed swiftly like some golden cinematograph, leaving a blacker darkness behind and around them. One ruby-red spot shone upon the road, but no number-plate was visible within the dim ruddy halo of the tail-lamp which cast it. The car was open and of a tourist type, but even in that obscure light, for the night was moonless, an observer could hardly fail to have noticed a curious indefiniteness in its lines. As it slid into and across the broad stream of light from an open cottage door the reason could be seen. The body was hung with a singular loose arrangement of brown holland. Even the long black bonnet was banded with some close-drawn drapery. The solitary man who drove this curious car was broad and burly. He sat hunched up over his steering-wheel, with the brim of a Tyrolean hat drawn down over his eyes. The red end of a cigarette smouldered under the black shadow thrown by the headgear. A dark ulster of some frieze-like material was turned up in the collar until it covered his ears. His neck was pushed forward from his rounded shoulders, and he seemed, as the car now slid noiselessly down the long, sloping road, with the clutch disengaged and the engine running free, to be peering ahead of him through the darkness in search of some eagerly-expected object. The distant toot of a motor-horn came faintly from some point far to the south of him. On such a night, at such a place, all traffic must be from south to north when the current of London week-enders sweeps back from the watering-place to the capital--from pleasure to duty. The man sat straight and listened intently. Yes, there it was again, and certainly to the south of him. His face was over the wheel and his eyes strained through the darkness. Then suddenly he spat out his cigarette and gave a sharp intake of the breath. Far away down the road two little yellow points had rounded a curve. They vanished into a dip, shot upwards once more, and then vanished again. The inert man in the draped car woke suddenly into intense life. From his pocket he pulled a mask of dark cloth, which he fastened securely across his face, adjusting it carefully that his sight might be unimpeded. For an instant he uncovered an acetylene hand-lantern, took a hasty glance at his own preparations, and laid it beside a Mauser pistol upon the seat alongside him. Then, twitching his hat down lower than ever, he released his clutch and slid downward his gear-lever. With a chuckle and shudder the long, black machine sprang forward, and shot with a soft sigh from her powerful engines down the sloping gradient. The driver stooped and switched off his electric head-lights. Only a dim grey swathe cut through the black heath indicated the line of his road. From in front there came presently