No answer coming, she repeated her demand with more composure. Then a curious thing happened. A board creaked, and looking swiftly at the floor, I saw the imprint of a foot marked in the pile. It vanished and the pile sprang up again resiliently, but, twenty inches farther onward towards the girl, a second sole-shaped hollow formed itself and there remained. An instant's flashing search disclosed three others. I now knew for certain the position of my enemies, and with a wild heart-throb of joy I nerved myself for action. The shape of the footmarks showed me that both men faced the girl, and that they were standing about a yard apart. With two noiseless strides, I stepped behind the rearmost. Then I stooped and seized a pair of hard, lean thighs and heaved a body up and sent it hurling through the air above the second set of footprints. "I've got you again, you dog!" I cried; then stepped back swift and noiseless to my former place. The trick was perfectly successful. Silent, save for their heavy breathing and the trembling of their feet, the rascals writhed and stamped about the room, locked, doubtless, in a close embrace, although I could not see them. As for me, I slipped presently to a chair, caught it up, and guided by a sound, I brought it crashing down upon the head of one of them. There followed a heavy groan, then a dagger blade flashed out of nothingness and once, twice, thrice, it rose and fell. Murder was being done before my eyes, but I had only half a mind to stay it, and indeed, before I could the knife had vanished into mist again, and all to be seen was a dark flow of scarlet fluid that welled in air and sank upon the carpet. I waited spellbound. Which was alive--which was dead? Belleville's voice put the question at rest suddenly. "Well done, Ptahmes," he gasped in Arabic. "He had me throttled when you struck. You shall have fifty pounds for this day's work." "Thanks, good master." I returned and edged towards his voice. But at that moment Miss Ottley fell in a swoon, and death could hardly have availed to keep me from her side. With a bound I was across the room, and in another second she was in my arms. Belleville must have seen, but thinking me the Arab, instead of chiding, he commended me. "Carry her to the laboratory," he commanded. "I'll follow with this carrion. We must dispose of it. Nay, wait. I'll go first. Damn him, how he bleeds!" he added in English. Then a little later, "He is wonderfully light for so tall and strong a man."