Tunnels 02, Deeper

opening in the cavern wall, metal ramps descending on either side of it from some structure above. Will couldn't see enough in the murkiness to be sure if it was a way out.
    "I can't tell what's there," he said to Cal. "Too dark."
    "That's exactly why we should go there," his brother replied.
    "But what if the Colonists come out before we reach it?" Will asked. "There's no way they can miss us."
    "They're on a break," Cal replied, shaking his head at Will. "We'll be OK if we go right now."
    Chester chimed in. "We could always back off... into the tunnel again and wait until the train's gone."
    "That could be hours. We've got to go now ," Cal said, his voice brimming with irritation. "While we've still got the chance."
    "Hang back," Chester immediately countered, turning to Cal.
    "Go now," Cal insisted tetchily.
    "No, we--" Chester came back at him, but Cal raised his voice and didn't let him finish.
    "You don't know anything," he sneered.
    "Who died and made you boss?" Chester swiveled around to his friend, looking for support. "You're not going to listen to this, are you, Will? He' just a stupid brat."
    "Shut up," Will hissed through gritted teeth, his eyes on the station.
    "I saw we--" Cal declaimed loudly.
    Will shot out his hand and clapped it roughly over his brother's mouth. "I said shut it, Cal. Two of them. Over there," he whispered urgently into Cal's ear, then slowly took his hand away.
    Cal and Chester sought out the two railwaymen, who were standing under a portico that ran along the front of several of the station buildings. They had just emerged from one of the shacks, and strains of bizarre music filtered across to the boys through the open door.
    They were wearing bulky blue uniforms and some type of breathing apparatus over their heads, and as the boys watched they lifted these up so they could drink from the large tankards each of them had in his hands. Even from where the boys were positioned, they could hear the men's grumbling tones as they stepped a few paces forward and stopped, idly perusing the train, and then turned to point out something in the gantry high above it.
    After several minutes, they turned on their heels and went back inside the shack, slamming the door behind them.
    "Right! Let's go!" Cal said. He chose to look only at Will, studiously avoiding Chester.
    "Cut it out," Will growled. "We go when we all decide. We're in this together."
    Cal started to reply, his upper lip lifted in an aggressive snarl.
    "This isn't some children's game, you know," Will shot at him before he could speak.
    The younger boy huffed loudly and, rather than continue to challenge Will, turned on Chester, glowering fiercely.
    "You... you Topsoiler!" Cal spat.
    Chester was completely unfazed by this and, raising an eyebrow, gave Will a small shrug.
    So they remained there, Will and Chester carefully watching the frontage of the station while Cal drew pictures in the dirt that had a remarkable resemblance to Chester, with squarish bodies and blocky heads. Every so often he chuckled evilly to himself and wiped them over, only to begin drawing again.
    After five minutes with no further sign of the railwaymen, Will spoke. "Right, I reckon they've settled in. I say we should go now. Happy, Chester?"
    Chester gave a single nod, looking distinctly unhappy.
    "At last," Cal said, leaping to his feet and rubbing his hands together to shake off the dust. In an instant he was in the full glare of the lights on the open ground, striding cockily away.
    "What's his problem?" Chester said to Will. "He's going to get us all killed."
    In the darkness by the cavern wall, they stepped between the pair of ramps and discovered that there was indeed a way through, a sizable cleft in the rock. Cal had struck it lucky with his suggestion and wasn't going to let this go unnoticed.
    "I was r--" he started.
    "Yeah, I know, I know," Will interrupted. "This time."
    "What are those?" Chester said, noticing a number of structures as they entered a new stretch of tunnel. They were almost buried by large drifts of silt along one side of the wall. Some were like huge cubicles and others were circular in shape. Odd pieces of metal and debris lay discarded around them. The boys approached one of the structures, which, close up, looked like a giant honeycomb built of gray brick. As Will was wading through the silt to get closer, his foot flipped something over. He stooped to retrieve whatever it was. Hard, flat, and with undulating edges, it