"What the--what are you driving at, my dear chap?" ejaculated the Superintendent excitedly, stooping at the pressure of Cleek's arm upon his shoulder. "This--spinning-wheel thing? You don't mean to tell me that _It_ murdered Sir Andrew, do you? Because I'm not fool enough to believe _that_ story--and not dunderhead enough to be taken in by a practical joke. What _do_ you mean, old chap? I'm on pins and needles to know." "And it's just those particular pins and needles of yours which have found the thing out," returned Cleek in the sharp staccato of excitement. "Look here! It's as easy as A B C--once you've got the hang of it. And that sensation of yours _was_ an electric shock all right. And it was just this spinning wheel which gave it to you. The thing's wired--see? Devilishly well done, too, and disguised very successfully. But here it is. Under the wheel. And see that funny box-like thing attached, which looks as though it belonged to a part of the machinery?--and doesn't. That's a battery, by all that's good! Now, what the dickens does that battery do, I'd like to know?... 'A whirring sound'--'hum-hum-hum!' That's how they described it to me this morning, do you remember? Gad! And this is the thing that produced that supernatural sound, then! Just a touch of a switch somewhere, and the thing sets in motion. Now let's follow this wiring along to its destination, and that will tell us a good deal." He traced the line of palish flexible wire--so nearly the colour of the old wood as to be hardly discernible unless one really knew of its presence, round the wheel, and down on to the floor--the thing stood a mere matter of inches from the window-sill--and then disappeared up through a narrow piece of oak-coloured woodwork which was entirely unnoticed from the panelling it covered, until it reached the window-ledge and ended at the extreme right-hand corner of the middle window, and vanished in a cluster of ivy which clung about the outside of it, sending its tendrils right up to the edge of the sill itself. Mr. Narkom followed the thing with fascination, poking a finger here and there to help discern its threadlike and imperceptible progress, and was almost as quick as Cleek in leaping out through the low sill to the flower-bed below upon which those tell-tale footprints had made such a strong impression. Then, of a sudden, they both stopped and stared blankly at each other. For the end of the thing lay beneath the ivy covering, in a little home-made switch which, touched by the finger, obviously set the whole contraption in motion. Cleek hopped back into the room to see that no one was about, but the constable in charge stood outside the door, not in it, and they had closed that door carefully behind them upon entrance. Then he leaned out over the top of the window-sill and spoke softly to Mr. Narkom.