Tunnels 04, Closer

the middle until we find it," he said.
    It took a few minutes before Chester eventually located it. He called Drake over.
    "Good. That's it. Right -- slip your Bergen off and put it down here," he said, pointing to the floor next to the panel. Then he opened up the Bergen, and ever so carefully lifted out a pair of objects encased in sleeves of a blanket-like material.
    "Are those gas cylinders?" Chester asked.
    Drake nodded as he screwed transparent plastic pipes into the valves on the top of each of the cylinders, which were both around thirty centimeters in length. He placed the cylinders under the panel, then stopped as he thought of something. "You should have these... just in case," he said, extracting a couple of small khaki-green tubes from his belt kit and handing them over.
    Chester examined the writing on the sides of the tubes, but had no idea what it meant. "Atro... atrop..."
    "They're atropine injections. If something goes wrong, and you're exposed to what's inside the cylinders, yank the end off one of those field hypodermics and whack it into your thigh. It'll give you a shot of the atropine compound, which will counter the effects of the nerve gas."
    "Nerve gas?" Chester said, glancing nervously at the cylinders. "I was carrying nerve gas on my back?"
    "Yeah, under monstrously high pressure, too," Drake replied, as he saw Chester's horrified expression. "But what's in the other Bergen you lugged down to the EternalCity is far worse -- enough plastic explosive to vaporize every molecule of your body. If that'd detonated, there'd be nothing left of you to bury," he added, with a wry smile.
    As Chester shook his head, Drake took a box from the Bergen and opened the lid. Chester saw that it contained clamps. Getting down onto the ground, Drake slid below the panel and began to attach the clamps to the brass pipes, screwing each of them into place. "I'm cutting into the air lines now. Just keep an eye on that door in case anyone decides to show up," Drake said, his voice muffled as he continued to work under the panel.
    It took him a few minutes to make sure the clamps were firmly attached, then he slotted the transparent pipes from the two cylinders into them.
    "Time for the gas masks again, Chester," he said, as he emerged from under the panel. "And we don't take them off, not for anything." Once they had both donned their respirators, he loosened the valves on the cylinders of nerve gas. Each time there was a small hiss, but nothing more as the thrumming noise of the machinery in the gallery continued unabated.
    "Is that it?" Chester said, expecting more.
    "Yeah, that's it," Drake confirmed. "I've tapped the nerve gas straight into the air supply for the South Cavern -- it'll circulate everywhere but the Styx Citadel and the Garrison, which have their own supplies. You see, just a few parts per million of this stuff in the atmosphere down here will be enough. And it's odorless, so nobody will be able to tell it's there."
    "But what will it do to the Colonists?" Chester asked. "Will it harm them?"
    "No, nothing serious, except maybe for some nausea and vomiting in a handful of cases. No, in less than half an hour, the Colonists will be waking up with flu-like symptoms -- chronically watering eyes and runny noses -- which will last for the rest of the day. The main point is that they won't be able to see anything much, and certainly won't be in any state to stop of couple of Topsoilers trespassing on their manor."
    Drake checked his pistol. "And if we happen to bump into anybody, we only use the tranquilizer rifles and handguns," he told Chester. "We' re not here to injure any Colonists." He lifted his Bergen onto his back. "Right, Chester old man, let's go and have some fun."

    * * * * *

    "What on earth are you doing round here so late?" the guard in the sentry box asked, standing up. He frowned at the Second Officer, and then noticed Colly by his side. "Ah, I've got it. You took the Hunter out for a walk, and you wandered a bit too far from home? You're lost!"
    The guard's broad shoulders shook, but he didn't make much sound as he laughed. The notion of anyone who'd spent their whole life in these underground caverns losing their way amused him, although there was also concern in his eyes as he regarded the Second Officer.
    "I have been walking around for a while -- that's true," the Second Officer admitted, as he scratched the white stubble on his chin. He averted his eyes from the guard, as if he