The man, continuing to flash his light about, plainly had heard nothing, and the curtains had prevented him from being warned by the chill of the night air that the window was open; but now, at the further side of the room, another electric torch flashed out. Another man had been in the room; he neither alarmed nor was alarmed by the man flashing the first light; each had known the other's presence before. There were at least two men in the room, working together--or rather, one was working, the other supervising; for Eaton heard now a steady, almost inaudible grinding noise as the second man worked. Eaton halted again and waited; if there were two, there might be others. The discovery of the second man had not made Eaton afraid; his pulses were beating faster and hotter, and he felt the blood rushing to his head and his hands growing cold with his excitement; but he was conscious of no fear. He crouched and crept forward noiselessly again. No other light appeared in the room, and there was no sound elsewhere from the darkness; but the man who supervised had moved closer to the other. The grinding noise had stopped; it was followed by a sharp click; the men, side by side, were bending over something; and the light of the man who had been working, for a fraction of a second shot into the face of the other. It did not delay at all; it was a purely accidental flash and could not have been said to show the features at all--only a posture, an expression, a personality of a strong and cruel man. He muttered some short, hoarse imprecation at the other; but before Eaton heard the voice, he had stopped as if struck, and his breath had gone from him.