"Shoot straight," remarked Dr. Dillon, a few minutes after, "we shan't have such a good chance long. The gate is almost gone. Then most of the game will be out of range--too close to the wall. And once they get into the tunnel we shall have to sound _cease firing_ until they come out on the other side; but then we ought to do decent damage, if the prisoners don't get at us first." He paused, and shot on steadily till, with a hoarse shout, the attackers surged inwards. Then he laid his rifle aside, remarking that it would be as well to keep an eye gaolwards, in case of complications. So far as could be seen in that curious chequering of dense darkness and sharp glittering light; light which was palpably an intruder, which seemed absolutely apart from the things it showed--even from the dust-atoms--there was none as yet. At least the uppermost portion of that vast wheel of wall stood out, perfect, unbroken. The roof of the Smiths' bungalow, where the light stood, being, however, but little higher than these walls, much of what lay below in the sections themselves was necessarily hidden in shadow; especially on the side nearest the light. But the narrow alley leading up to the central tower, being in straight line with the ray, showed clear as daylight, save just under the citadel itself. So did most of the little courtyard, with its doors opening to the right and left. George Dillon gave a sigh of satisfaction at the sight, since, whether the foe elected--when once inside the gates--to rush the roof, or press on to liberate the prisoners by those six doors in the round tower, there would be fair chance of a good bag, for a straight shot! Or, even if the convalescents in hospital were to set free the solitary-cell convicts--a contingency which had occurred to him too late for any plan of minimizing the danger--and were to swarm into the courtyard to help against the last gate (which, of course, was partly barred from the inside), he could settle their hash also. And that, now, was his one idea. The idea of all brave men when they find themselves in a tight place--to kill before being killed. As yet, however, there was no sign of life even within the vast wheel, with its rims and spokes of light, its centre of shadow. It lay dim, curiously still behind the dust-atoms that danced in the ray, like motes in a sunbeam. There was not a sound, not a sign within. Only the tumult of voices, the intermittent shots without, rising above the dull, muffled hum in the air. Stay! that was something. Half way round the circle, where the shadow of the tall tamarisk tree in the Smiths' garden cut a jagged gap in the white rim of wall, there was some change, something that had not been there a moment ago.