Tunnels 01, Tunnels

took out his map and compass while Cal kept watch.
    "I've no idea where we are," he admitted, tucking the map away. "It's hopeless!"
    "We could be anywhere," Cal agreed.
    Will stood up, looking left and right. "I say we carry on in the same direction."
    Cal nodded. "But what if we end up right back where we started?"
    "Doesn't matter. We've just got to keep moving," Will said as he set off.
    Once again the silence crowded in on them, and the mysterious shapes and shadows appeared and softened as if the buildings were pulling in and out of focus in this invisible city. They'd made tortuously slow progress through a succession of streets when Cal came to a standstill.
    "I think it's clearing a little, you know," he whispered.
    "Well, that's something," Will replied.
    Once again Bartleby stiffened and crouched down low, hissing as the margins of the fog rolled back before them. The boys froze, their eyes feverishly raking the milky air.
    As if veils were being lifted to reveal it, there, not twenty feet away, a dark, shadowy form was hunched menacingly. They both heard a low, guttural growl.
    "A stalker!" Cal gulped.
    Their hearts stopped with awful realization. They could only watch as it rose up, its muscular forelegs tensing into life as it pawed the ground, then began to move, accelerating forward at a bewildering speed. There was absolutely nothing they could do. There was no point in running; it was too close. Like an infernal steam engine, the black hound was pounding toward them, condensation spewing from its flaring nostrils.
    Will didn't have time to think. As he saw the dog spring, he dropped his backpack and shoved Cal out of the way.
    The stalker soared through the air and slammed heavily against Will's chest. Its clublike paws knocked him flat on his back, his head thwacking the algae-covered ground with a hard slap. Half stunned, Will reached up and grasped the monster's throat with both hands. His fingers found its thick collar and hung on to it as he tried to hold the brute away from his face.
    But the animal was just too powerful. Its jaws snapped at his mask, then caught on to it and bit down. Will heard the squeal of its fangs tightening on the rubber as the mask was crushed against his face, and then a pop as one of the eyepieces shattered. He smelled the putrid breath of the stalker, like warm, sour meat, as the animal continued to wrench and twist the mask, the straps behind Will's head stretched almost to the breaking point.
    Praying the mask would stay in place, he tried with all his might to turn his head away. The stalker's jaws slid off the wet rubber, but Will's success was short-lived. The dog pulled back slightly, then immediately lunged again. Screaming, and still hanging on to its thick collar with all his might, Will was barely managing to keep it away from his face, his arms at the very limit of their strength. The collar was cutting into his fingers -- he couldn't believe how heavy the beast was. Time after time, Will whipped his head away, only just evading the snapping teeth, like the jaws of a powerful trap clapping shut.
    Then the animal contorted and twisted its body.
    One of Will's hands lost its grip, and with nothing to hinder it the animal quickly sought out a more rewarding target. It caught hold of Will's forearm and bit down hard. Will cried out from the pain, his other hand involuntarily opening and letting go of the collar.
    There was nothing to stop it now.
    The animal instantly scrabbled over him and sank its incisors into his shoulder. Amid the growling and biting he heard the cloth of his jacket rip as the huge teeth, like twin rows of daggers, penetrated and tore into his flesh. Will wailed again as the animal shook its head, snarling loudly. He was helpless, a rag doll being shaken this way and that. With his free arm, he punched weakly at the animal's flanks and head, but it was no use.
    Then suddenly the dog detached itself from his shoulder and reared up over him, its huge weight still pinning him down. As its frenzied eyes fixed on his, he could see its slathering jaws just inches from his face, strings of its drool dripping into his eyepieces. Will was aware that Cal was doing all he could to help; he was quickly lunging in to pummel and kick at the beast, then just as quickly pulling back. Each time he did this, the dog merely half turned to snarl at him, as if it knew Cal posed no threat. Its small, savage brain was fixed on only one thing; the kill that was