The tunnel entrance he was heading for had once been a wide opening, drilled laterally into the side of the cliff, and big enough to allow easy access to the tunnels, so that the passengers of those old underground trains could get to the platforms where they stopped. But the sun bomb had changed all that. The concussion had shaken loose rock at the top of the cliff and a minor avalanche had obliterated all indications of the tunnel's existence, except for one small, narrow opening near the top of what had once been a wide hole in the face of the cliff. Stanton walked slowly toward the spot until he was finally at the base of the slope of rock created by that long-ago avalanche. "Up there?" he asked. "That's right," said Captain Greer. "I think I'll leave the rifle here, Barhop," Stanton said. "No point in carrying it up the slope." "Right. Put it in those bushes to your left. They'll conceal it, won't they?" "I think so. Yeah." Stanton hid the rifle and then began making his way up the talus slope. Captain Greer flipped a switch. "Team One! He's coming in. Are those alarms deactivated?" "All okay, Barhop," said a voice. "This is Leader One. I'll meet him at the hole." "Right." Captain Greer reversed the switch again. "Are you ready, Barbell?" Stanton looked into the dark hole. It was hardly big enough to crawl through, and ended in a seeming infinity of blackness. He took the special goggles from the case at his belt and put them on. Inside the hole, he saw a single rat, staring at him with beady eyes. "I'm ready to go in, Barhop," Stanton said. He got down on his hands and knees and began to crawl through the narrow tunnel. Ahead of him, the rat turned and began to lead the way. _[22]_ The big tunnel inside the cliff was long and black, and the air was stale and thick with the stench of rodents. Stanton stood still for a minute, stretching his muscles. Crawling through that cramped little opening had not been easy. He looked around him, trying to probe the luminescent gloom that the goggles he wore brought to his eyes. The tunnel stretched out before him--on and on. Around him was the smell of viciousness and death. Ahead ... _It goes on to infinity_, Stanton thought, _ending at last at zero_. The rat paused and looked back, waiting for him to follow. "Okay," Stanton muttered. "Let's go." The rat led him down the long tunnel, deep into the cliffside, until at last they came to a stairway that led downward into the long tunnels where the trains had once run. They came to the platform where passengers had once waited for those trains. Four feet below the edge of the platform were the rusted tracks that had once borne those trains. He lowered himself over the edge to stand on the rail. "Barbell," said a voice in his ear, "Barhop here. Do you read?" It was the barest whisper, picked up by the antennas in his shoes from the steel rail that ran along the floor of the dark tunnel. "Read you, Barhop."