"He was seen. And pursued. But he got away easily, heading north. The island was searched, and the police were ready to start an inch-by-inch going over of the island two days later. But the Nipe hit and robbed a chemical supply house in northern Pennsylvania, killing two men, so the search was called off. [Illustration] "It wasn't until two years later, after exhaustive analysis of the pattern of his raids had given us something to work with, that we decided that he must have found an opening into one of the tunnels up here in the game preserve." He gestured again at the map. "It wouldn't take him long to see that no human being had been down there in a long time. It was a perfect place for his base." "How does he move in and out?" Stanton asked. "This way." The colonel traced a finger down one of the red lines on the map, southward, until he came to a spot only a little over two miles from the southernmost tip of the island. The line turned abruptly toward the western edge of the island, where it stopped. "This tunnel goes underneath the Hudson River at this point, and emerges on the other side. It's only one of several that do so. They're all flooded now; the sun bomb caved them in when the primary shock wave hit the surface of the river. "In spite of his high rate of metabolism, the Nipe can store a tremendous amount of oxygen in his body, and can stay underwater for as long as half an hour without breathing apparatus--if he conserves his energy. When he's wearing his scuba apparatus, he's practically a self-contained submarine. The pressure doesn't seem to bother him much. He's a tough cookie." Stanton nodded silently and slowly. Could he beat the Nipe in hand-to-hand combat? There would be no way of knowing until the final moment of success or failure. "At that time," the colonel went on, "we hadn't formulated any definite policy on the Nipe. We didn't know what he was up to; we weren't even sure he was actually down in those tunnels. We had to find out." He walked over to the nearby table and opened a box some twelve inches long and five-by-five inches in cross section. "See this?" he said as he took something out. It looked like a large dead rat. "Our spy," said Colonel Mannheim. * * * * * The rat moved along the rusted steel rail that ran the length of the huge tunnel. To a human being, the tunnel would have seemed to be in utter darkness, but the little eyes of the rat saw its surroundings as faintly luminescent, glowing from the infra-red radiations given out by the internal warmth of cement and steel. The main source came from above, where the heat of the sun and of the energy sources in the buildings on the surface seeped through the roof of the tunnel.