Tunnels 03, Freefall

at the best of times, were stained and filthy, and her face was lined with fatigue. Will watched as her eyes slid shut.
    "Hey, Martha," he said gently.
    Her eyes flickered open and she turned to the bridge. "We cross one at a time. And no talking -- we have to keep the noise down from here on in." She took out some Aniseed Fire, but didn't make a move to light it. "Save it," she said, as if reminding herself what she ought to be doing. Then she edged forward, the bridge rocking as she began to cross it.
    It was Chester's turn once she was safely on the other side. The boys had decided between them that as Chester weighed the most, he shouldn't attempt crossing with Elliott. Instead he took one of the lighter rucksacks with him.
    "I'm not happy," he grumbled as he started across. "Not happy at all."
    "Safe as houses," Will told him confidently.
    "Oh, brilliant, that's the kiss of death. I'm bloody doomed now you've said that," he groaned, raising his eyebrows at Will, who gave him a nod to wish him luck.
    From where he was standing, Will could see that Chester's weight was making the bridge say. And even though Chester was taking it slowly, the bridge swayed alarmingly and made such loud creaking noises, Will thought the whole thing was going to come crashing down at any moment. But the boy stopped frequently, allowing the bridge to settle down before he continued again, and eventually made it safely to the other side.
    Then came Will's turn. Picking up Elliott and the stretcher, he ventured forward. He'd gone twenty steps when he had to stop. He stood as rigid as a statue. There were two guide ropes on either side of the bridge at waist height and Will longed to grip one of these, but he couldn't because his arms were full with Elliott.
    "It's a long way down," a voice in his head boomed so loudly he flinched, and then just the thing he didn't want to happen happened. The irrational urge was back, and it was as if he was suddenly under the control of some puppet master. He could so vividly picture himself pivoting over one of the guide ropes and tumbling into the velvety, welcoming darkness below. Somehow, it made such perfect sense. For several seconds he wasn't aware of anything else, just the overwhelming attraction of the empty air below him as it tried to suck him down. He hadn't a thought for Elliott who was totally at his mercy, or for Chester and Martha on the other side or the crevasse; there was only him, and the persuasive, irresistible pull. The, in that small portion of his brain that was still cogent, he forced himself to consider Elliott and how wrong it would be to take her with him. But it wasn't enough -- the compulsion was too strong.
    "Please," he whimpered. "Please, no."
    Then something nudged him from behind, and he swiveled his head stiffly round to see what it was. Bartleby's face was there, his big eyes peering at him with incomprehension. The cat had obviously decided that it was time for him to cross, and couldn't understand why Will was stationary and blocking his way. As Will locked eyes with the cat, the animal gave a low meow -- with an intonation that made it almost human; he could have been saying, 'Why?'
    Will blinked, and the urge flickered like a candle flame in the wind, and then was extinguished. He swung around to see Chester poised at the other end of the bridge. Will began forward again, the cat treading softly behind him, nudging the boy when he thought he was moving too slowly.
    As Martha had told them not to speak, Chester didn't say anything when Will was back on terra firma again, but his concern showed in his eyes. Will stumbled a little way down the tunnel where he put Elliott down, then slumped to the ground beside her, his head in his hands.
    Once Rebecca had joined them they were ready to move on. They hadn't gone far when they noticed that they were walking on fungus again, and then they were almost immediately faced with the prospect of three successive vertical drops. Will was still feeling drained after the incident on the bridge, and the thought of carefully lowering Elliott and the stretcher down each one was almost too much to contemplate. It wasn't another outbreak of the urge that troubled him -- for some reason, that didn't reappear -- it was the amount of planning associated with each maneuver. And the slippery surface of the fungus only added to their difficulties. By the time they'd finished the third and final descent, Will was fit to drop, but by her