At first it was but a lurid spark upon the stone pavement. Then it lengthened out until it became a yellow line, and then, without any warning or sound, a gash seemed to open and a hand appeared, a white, almost womanly hand, which felt about in the centre of the little area of light. For a minute or more the hand, with its writhing fingers, protruded out of the floor. Then it was withdrawn as suddenly as it appeared, and all was dark again save the single lurid spark which marked a chink between the stones.

Its disappearance, however, was but momentary. With a rending, tearing sound, one of the broad, white stones turned over upon its side and left a square, gaping hole, through which streamed the light of a lantern. Over the edge there peeped a clean-cut, boyish face, which looked keenly about it, and then, with a hand on either side of the aperture, drew itself shoulder-high and waist-high, until one knee rested upon the edge. In another instant he stood at the side of the hole and was hauling after him a companion, lithe and small like himself, with a pale face and a shock of very red hair.