Tunnels 04, Closer

snapped, panic evident in her voice.
    She pointed at the pieces of rock. They were lying in a row.
    Will was immediately concerned. "What is it?"
    She snatched the lantern from him, and tore back through the arch and down the short flight of steps. In a second she'd found what she'd been looking for on the rocky ledge behind the base of the wall. "I knew it! Look!" she cried.
    "So what?" Will asked.
    Elliott shook her head. "It's Limiter procedure. That's how they mark the trail for other soldiers. Textbook stuff."
    "But surely the Rebeccas and first Limiter could have left th--" Will tried to suggest.
    "No way! I went over every inch of this place when I first found it. I wouldn't have missed something like this." She swung her rifle from her shoulder and cocked it. "Will, you know what this means, don't you?"
    He really didn't want to hear what she was about to say.
    "It means that we've got more Limiters with us in this world. It's not over yet."

    * * * * *

    Carrying a tray, Eddie approached the end of the basement where Drake was working. Perched on a stool, Drake had the parts of the Dark Light he'd taken apart carefully arranged on the bench in front of him. After spending the morning evaluating the items Eddie had collected together in the basement, Drake had concentrated all his efforts on the Styx interrogation device. He'd gone off to fetch his test equipment and had used it to examine each component as he extracted it. So far the exercise had taken him most of the afternoon.
    "Thought you might be hungry," Eddie said as he placed the tray on the bench.
    "Yeah... thanks," Drake mumbled.
    "Making progress?" Eddie asked.
    "Slowly but surely," Drake replied, wiping his forehead. "This is a very clever piece of kit. I've never seen the likes of some of these components before." He reached across the bench to pick up a small metal cylinder with rounded ends. "There are four of these in the base of the Dark Light. Have you any idea what they do?"
    "No. My job was to use the Dark Light on subjects -- nothing more," Eddie said. "Were you ever Darklit?"
    But Drake didn't reply, completely absorbed by the cylinders to the exclusion of all else. "When I pass a charge through them, these ionizing tubes emit different wavelengths. The spectrum for each tube is incredibly narrow, incredibly specific. When all the tubes are in full swing, the combination of the four spectra is unique, and I reckon I might be able to rig something up to detect them."
    "To what end?" Eddie asked.
    "As long as it's above ground, I should be able to tell when and where Dark Lights are being used." He put the metal tube down and straightened up, stretching his arms.
    Eddie didn't show any signs of leaving as he hovered on the other side of the bench. Drake shot a glance at him. "You look like you want to ask me something?"
    "Yes, about Elliott. You said there's a route down to the area beneath the Deeps, and I want to know more about it, and how we're going to proceed."
    "Sure. Let's talk about it later," Drake said dismissively. Sliding from the stool, he crossed to an adjacent bench. "Eddie, tell me about these. I found a box of them." He held up a fistful of vials by their cords. They were identical to the pair Will had been given by the Rebecca twins, although the silver stoppers on these hadn't been painted.
    "They're receptacles for viral agents," Eddie answered. "The clear liquid you see in them is a compound manufactured by the Scientists. They call it a static -- it keeps a virus alive, even though it's outside the body of the host."
    "Yes, I had some of it assayed when we couldn't figure out how they'd managed that," Drake said, moving rapidly on to some items he'd put on the end of the bench. "And these?" he asked, indicating a group of bottles several centimeters in length, with sealed tops. Inside each was a small object suspended in yellow fluid. "I'm no zoologist, but these look suspiciously like snails. What's their significance?" Drake asked.
    "They are snails -- Plague Snails . Their natural habitat is the vegetation around the perimeter of the EternalCity. I often went into the city with patrols from the Division. And on a couple of occasions, we were there on handholding duty, looking after parties of Scientists. You see, they collect the snails, for the viral strains they harbor."
    "You're telling me these are the original source of the Dominion virus? These are the vector?" Drake asked eagerly.
    "Not these snails