And then Nick could see the water itself. He ran on toward the northwest border where the terrain was lowest, trying to keep his mind on the desperate business ahead. His spirits lifted slightly as he realized that Susan had reached Merlo. But what had happened to her then? She had still defied the Council. His feet struck wet sand, then shallow, murky water while he was still a hundred yards from the barrier. He waded on as the water deepened. Only a few scattered lights still gleamed as he stopped to adjust his improvised diving mask. Evidently the water was reaching the central power plant, but flares arched upward at irregular intervals to shatter the night. During the intervals of brightness Nick froze to immobility. The gunners in the guard towers were firing at shadows. But no explosive bullets, for which Nick was especially glad as a stream of lead whipped the water nearby. There was a standing order forbidding the use of explosive shells where they might damage the barrier wires. So far the firing was desultory, bursts coming only when the barrier sparked as the water deepened. Evidently the commander still considered the flood merely a freak of nature. All at once there was no more ground beneath his feet. Nick began to swim. A yell of alarm that changed to a shriek of agony cut the air, coming from the southern border of camp. Another. The firing grew suddenly intense, lines of red and yellow tracer whipping out from the towers. A flare exploded overhead to disclose a shadow like a giant bat that swooped heavily across the barrier and fell upon a Mec just inside. The man's automatic rifle roared a futile, unaimed burst as he died. The Martians themselves Nick could not see. Dazzled by the intermittent glare, he almost swam into the barrier without seeing it. Only the barrier itself saved him as the rising water engulfed another wire and the lethal current popped and sparked. With a heave of his shoulders he swung aside and glanced up. Ten or twelve feet of the fence's thirty foot height still projected above the surface. He floated, tightening his mask until the nosepiece dug into his face. Then he pushed the clip down over the valve, and as the life-giving gas hissed out closed his eyes and let himself sink into the silt-filled, inky water. Bubbles spurted around the edge of the mask and roared upward past his ears, but he found that by inhaling slowly he could breathe. His feet touched bottom and his legs sank in almost to the knees. The fine, dusty sand of Mars that had lain arid for so many centuries had changed to clinging, sticky mud. He pulled himself free and swam forward anxiously along the bottom. One outstretched hand found the barrier. He felt the prick of the hooked, knife-edged barbs as they sank through the cloth with which he had wrapped his hands. He advanced the other more cautiously. Here below the surface the killing current of the barrier was dead, shorted away by the dirty water.