Gordon stooped suddenly, and held up his hand. Mark could hear nothing but the faint murmur of the stream as it flowed beside them.
'Someone running,' Gordon said.
He grasped Mark's arm, and drew him back against the wall, puzzled and silent. Mark had not been long enough in the caves to realise that something unusual must be afoot. For a man to run here was all but unknown. Why should he? In this place time could neither be lost nor gained: it did not exist. Now he began to distinguish the sound of footsteps which would soon overtake them. Both watched the last corner expectantly. The sound grew louder.
'Only one,' said Gordon. He bent down to pick up a piece of rock, settling it firmly in his hand.
A form clad in flowing, grey tatters rounded the corner.
It came on until it caught sight of them, flattened against the wall. It stopped abruptly. Gordon dropped his stone, and stepped out.
'Mahmud!' He called in surprise.
The Arab approached, somewhat out of breath.
'What is it?' Gordon asked, joining him. The three walked on together.
'Miguel,' explained Mahmud excitedly. 'I've been talking to the pygmies; I found some of them who hate him, and I got it from them.'
'Well, what was it?' Gordon was impatient.
'Miguel's trying to find out where the tunnel is.'
'We knew that—what else could he have been trying to find out?'
'But there's more than that. He's got several of his friends and most of the pygmy prisoners behind him, and they've been bargaining with the pygmies outside. Miguel offered to show them our tunnel in exchange for his freedom, but they didn't like that, so he compromised. He would show them the tunnel if they would take him out of the prison system and give him the run of the ordinary caves.'
'That wouldn't do him much good.'
'He and his friends think it would—they've probably got an idea of his getting out somehow, and bringing help. Anyhow, the bargain's been made.'
Gordon stared. 'It has?'
'It has.'
'So that's what he's been up to, is it? He's a fool if he thinks they'll ever give him a chance of getting right outside.'
'But he's got some scheme—you can be sure of that.'
'Does he know yet where the passage is?'
'No, but-'
'With an incentive like that it won't take him long to find out, eh?'
The Arab nodded.
'Then he'll have to be dealt with,' Gordon went on.
'You mean, kill him?' Mark asked.
'I do—he's a rat.'
'But his friends—won't they take up the bargain?'
'We can treat all traitors alike.'
'And how far will that get you? As I see it, the real damage is done already—the pygmies know that the tunnel exists. It was only really safe while it remained unknown to them. The cat's out of the bag now, and I don't see that killing Miguel's going to do much good.'
'It he's not found the tunnel yet, it might. He's a long way the brightest of that gang. It'd set them back and give us more time. If he has found it, he must be got rid of at once before he can tell anyone else.'
'You won't be sure he hasn't told.'
'Sure enough. Miguel's kind keeps everything up its sleeve as long as it safely can. He'd be scared of the rest letting him down if he told them anything until the last moment.'
Gordon was still talking as they came to the first of the fungus caves, and Mark found himself almost as surprised as he had been when he saw the giant mushrooms in the outer caves. His memory had reduced their size, and despite his expectations, he was taken aback. He would have liked to linger and examine the fantastic picture they made, but his companions were in too great a hurry. Gordon led round to the right, keeping to the strip of open space, between the growths and the wall, where walking was easy. At no great distance they encountered a passage only a few yards long, and passed through it into another cave. Here, the scene was more open for much of the fungus had been cut away to be carried to the living caves where it would be rendered more easily edible by mashing or other processes. They Crossed the loam, littered with chips and stubs of felled fungi, to plunge into the still standing growths beyond. The going became slower and more awkward. Gordon warned Mark to step over the twining ground tendrils, and if possible to avoid bruising them. Not, he admitted, that there was any great need for care as yet, but it would be better not to leave a trail.
It was in the third fungus cave that he became really wary. He led a complicated path among the trunks and marrow-like objects, zigzagging and doubling continually. Mark did his best to imitate the skill which both he and the Arab showed in passing without trace, but he felt that he was making a poor job of it. He was responsible for a number of broken stalks and crushed tendrils, however, they were scattered, and it seemed unlikely that anyone could follow so tortuous a trail from so few clues. He realised at last why Gordon had used loud tones to announce that they were going to the fungus caves. They were an obvious sight for a newcomer, but somewhere hidden away among them was the beginning of the upward tunnel.
He was relieved when he could see, between the mushroom heads, the grey stone wall only a few yards ahead. A minute or two more, and they stood on the fringe of the vegetation.
The sound of a sudden scuffle caused them all three to turn sharply. Mark had a glimpse of a man who ran from the wall and disappeared between the trunks to their right. Mahmud, too, saw him. Before the full significance came home to the others, he was in swift, silent pursuit, with the rags of his burnous streaming behind him. Mark opened his mouth, but Gordon raised his hand. The two stood listening.
Mahmud vanished among the stalks by the track which the other had left. For some moments there was nothing to be heard but the thudding of feet, mingled with the muffled snapping of stalks and tentacles. The fugitive was blundering blindly ahead, trampling the lower fungi underfoot, and turning aside only for the thicker trunks. The slender stalks which he swept from his way, broke, not with sharp crack of branches, but dully, like rotten wood. The watchers could follow his trail by the way in which more than one tall, umbrella-like head shook and leaned to subside slowly into the lower growths. A cloud of white spores broke suddenly into the air; they could hear Mahmud splutter and cough as he came to them. A minute later followed a choked cry; a tremendous agitation and threshing amid the trembling stalks. Mahmud and the fugitive had come to grips.
'Come on,' Gordon said, starting towards the sound.
'Look,' called Mark, but the other did not hear. He was already away. Mark alone had seen another figure break from the hiding of a mushroom trunk, and speed away up the clear space beside the wall. He gave chase.
The second fugitive was wiser than the first. He had no intention of tangling himself in stalks; he was depending on speed and a start of thirty yards to carry him safely to an opening.
Mark pounded along. He was in poor form for violent exercise, and saw that he was barely holding his own. The man ahead glanced over his shoulder, and then put on a spurt. Mark tried desperately to increase his own speed, but his feet felt clumsy and heavy. He scarcely knew why this man must be caught, but the attitude of the others had shown it to be vital. The man had begun to slacken— such violent exercise was not encouraged by life in the caves. But his own rate, too, was falling off, and his heart thumping painfully; he tried desperately to force his lagging feet.
A pale, fat tentacle defeated him. It had grown out more adventurously than the rest. Mark's descending boot crushed it into a slibbery mess, and he pitched head first into the loam.
He sat up at once, brushing the dirt from his eyes, but the fugitive had gone, and he himself was too winded to continue. He remained where he was for some minutes recovering, before he rose to walk back to the others.