Tunnels 01, Tunnels

Then the rope was dropped for Will, who hauled himself into the shadows above. Once there, Will jumped up and down to shake off the water and warm himself.
    Then they slid down the convex ramp on the seats of their pants, landing with a thump on the ledge that marked the beginning of the rough stairs. Before proceeding, they carefully removed Bartleby's knitted clothes and left them on a high ledge -- they couldn't afford to carry any dead weight now. Will didn't really have any idea what he was going to do once they were back in the Colony, but he knew he had to be completely practical... he had to be like Tam.
    The boys put on their army surplus gas masks, looked at each other for a moment, nodded an acknowledgment, and with Cal leading the way they began the long descent.

    * * * * *

    The going was arduous at first, the stairs hazardous from the constantly seeping water and, farther down, the carpet of black algae. With Cal taking the lead, Will found he had very little recollection of their previous passage through, realizing that this must have been because the mysterious illness had already gotten a hold on him by then.
    In what seemed like no time at all, they had arrived at the opening to the cavern wall of the EternalCity.
    "What the heck is this? " Cal exclaimed the moment they walked out onto the top of the huge flight of steps, their eyes quickly sweeping down its dark course. Something was very wrong. Approximately a hundred feet below, the steps vanished from view.
    "That's what I believe they call a real pea souper," Will said quietly, his glass eyepieces glinting with the pale green glow.
    From their vantage point high above the city, they looked out on what appeared to be the undulating surface of a huge opaline lake. The thickest of fogs covered the entire scene, suffused by an eerie light, as if it were one immense radioactive cloud. It was very daunting to think that the vast extent of the huge city lay obscured beneath this opaque blanket. Will automatically scrabbled in his pockets for the compass.
    "This is going to make life a little difficult," he remarked, frowning behind his mask.
    "Why?" Cal retorted. His eyes crinkled behind his eyepieces as a broad smile spread across his face. "They won't be able to see us in all that, will they?"
    But Will's demeanor remained grim. "True, but we won't see them, either."
    Cal held Bartleby still while Will tied a rope leash around his neck. They couldn't risk him wandering off under these conditions.
    "You'd better hold on to my backpack so you don't get lost. And whatever you do, don't let go of that cat," Will urged his brother as they took their first steps in the fog, descending slowly into it, like deep-sea divers sinking beneath the waves. Their visibility was immediately reduced to no more than a foot and a half -- they couldn't even see their boots, making it necessary to feel for the edge of each step before venturing to the next.
    Thankfully they reached the bottom of the stairway without incident, and at the start of the mud flats they repeated the black-weed ritual, wiping the stinking goo all over each other, this time to mask the Topsoil smells of London.
    Traversing the edge of the marshland, they eventually bumped into the city wall and followed it around. If anything, the visibility was getting even worse, and it took them forever to find a way in.
    "An archway," Will whispered, stopping so abruptly that his brother nearly fell over him. The ancient structure briefly solidified before them, and then the fog closed up, obscuring it again.
    "Oh, good," Cal replied without an ounce of enthusiasm.
    Once inside the city walls, they had to grope their way through the streets, practically walking on top of each other so that they wouldn't become separated in the impossible conditions. The fog was almost tangible, sucking and rolling like sheets in the wind, sometimes parting to allow them the briefest glimpse of a section of wall, a stretch of water-sodden ground, or the glistening cobbles underfoot. The squelch of their boots on the black algae and their labored breathing through their masks sounded unnervingly loud to them. The way the fog was twisting and playing with their senses made everything feel so intimate and yet, a the same time, so removed.
    Cal grabbed Will's arm, and they stood stock-still. They were beginning to notice other noises all around them that weren't of their making. At first vague and indistinct, these sounds were