'My strength,' said Paulo, sticking out his chest and flexing his muscles.

Alex laughed. 'Yeah, well I need your strength more than they do. We'll be doing the heavy work. Come on, let's go.'

NINE

Paulo and Alex walked to the other end of the lagoon and started a systematic search of the fringe of rainforest which edged the beach. For nearly two hours, they worked their way along the forest fringe, moving in a series of small squares which always started and ended on the beach.

The trees were smaller and more widely spaced at the edge of the forest and sunlight penetrated through their branches to the forest floor, where dense undergrowth grew in the rich covering of leaf mulch. Alex and Paulo had to fight a way through and progress was frustratingly slow. The undergrowth was full of thorns and they kept a constant look-out for snakes. It was hard going, but it was also very successful. Because the trees were smaller and draped with vines, it was easy to climb up to the level where fruit or leaves grew and, every time they emerged from the forest, they brought something out with them.

When they took a rest after two hours, Alex and Paulo had gathered a good selection of supplies, which were laid out on the beach beside them. There was a bunch of small, green tropical bananas, a pile of enormous, glossy banana leaves, a few yams and mangoes, some cut vines and a big stack of green bamboo canes. It was a good result, but still Alex was starting to get worried. He had been searching all morning and still had not found the one thing he really wanted. A game trail. Once they had a game trail to follow, he was pretty sure it would lead them to fresh water.

Alex picked up a mango and split it open with his knife. He cut the flesh away from the flat stone at the centre of the fruit, then handed half of it to Paulo.

Paulo armed the sweat from his face. 'That is enough, I think?' he said, hopefully, nodding to the pile of supplies. 'We have found a lot.'

'No,' said Alex. 'We need to go back in.'

Paulo groaned. 'I knew you were going to say that.'

'Not yet, though,' grinned Alex. 'We'll rest a while first.'

Paulo immediately settled back against the trunk of the shady tree they were resting under and closed his eyes. Soon he was snoring gently. Alex was too worried to doze. Back home in Northumberland, listening to his father, he had been sure he could survive in a tropical rainforest. Now he was actually in that situation, he felt a lot less certain of everything. What if he had already stumbled right over a game trail without noticing it? Alex looked across at Paulo and felt slightly reassured. At least the South American had some practical experience of tropical conditions, but how could he sleep so easily? Alex scowled in irritation as he finished his half of the mango. He took out his knife and whittled two new wooden handles for the flexible saw, then he took a small piece of sandstone from his knife sheath and honed the blade of his knife until it was back to full sharpness.

When he had finished, Paulo was still deeply asleep, but Alex could not delay the search for water any longer. His head was thudding with pain again and he knew it was only partly caused by his scalp wound. A headache was also a sign of dehydration. He forced himself to his feet and woke Paulo. This time, he had decided that they would plunge into the forest and keep going on as straight a line as they could manage until they found what they were looking for.

By the time they stumbled onto a game trail, they were both sweating hard and panting for breath. Their arms were streaked with thin lines of blood from thorn scratches and the mixture of blood and sweat had attracted a cloud of whining mosquitoes.

'This is a game trail?' asked Paulo.

'Yes,' grinned Alex, still slightly dizzy with relief that he had found one. 'Quite a well-used one too.'

'How can you tell?'

'See all the tracks in the mud there?' asked Alex. 'They look like deer tracks to me. And see how there are no twigs or branches growing over the trail? That's because there's a regular flow of traffic moving along here. There'll be water at the end of this trail.'

'Infierno!' cursed Paulo, standing in the middle of the game trail and swatting mosquitoes. 'They are fierce – and so annoying!' He grinned. 'They remind me of my little sisters.'

'Here,' said Alex, bending and scooping up a handful of soft mud from the side of the trail. 'Use some of this. It might help.'

They smeared the mud all over their faces, necks and arms in a thick layer. It was wonderfully cooling and it did seem to give some protection against the mosquitoes.

'Ah, yes,' said Paulo. 'The mud pack. Good for the skin. I will be even more handsome after this.'

Alex gave Paulo a sideways glance, wondering whether he was serious. Paulo looked back at him, his face caked with stinking mud and his eyes dancing with amusement. He was sending himself up. Alex grinned and shook his head as he hammered a stick into the ground to mark the spot where they had come out of the forest. He was beginning to like Paulo. He might have a lazy streak a mile wide, but he worked hard when he had to and he always seemed to stay cheerful.

'How long left before we meet up with the others again?' asked Alex.

Paulo cleared the mud from the face of his Rolex watch. 'Just under half an hour.'

Alex stared along the game trail which led into the deeper, primary forest on the lower slopes of the mountain. There was water that way, he was almost sure of it, and water was essential to their survival. Without it, they would not live for more than three days.

'Right,' he decided. 'We'll give ourselves ten minutes to explore the trail before we turn back.'

They had taken only a few steps along the trail when a single, high shriek, full of pain and fear, rang out from somewhere up ahead. Instantly, the steady singing of the crickets was switched off and the forest was plunged into silence. Alex and Paulo froze where they stood.

'Dios Mio!' whispered Paulo. 'The girls!'

'No,' said Alex, relaxing a little as the crickets resumed their song. 'It came from further up the trail. An animal. A dying animal.'

'You mean something – killed it?' Paulo shuddered. 'Do we go on?'

Alex stared along the narrow track, trying to see what lay ahead, but the forest crowded right up to the edge of the trail. Finally, he shrugged. 'I think we must,' he said, starting to walk again. 'We have to find water.'

'And the animal?'

Animals mean water,' said Alex, over his shoulder.

Paulo hesitated, then grasped his stick more tightly and followed Alex. 'I hope the others are safe,' he muttered uneasily.

TEN

Amber shrieked loudly, then shrieked again.

'Eeeuuww! Get it off me! Get it off!'

Li rolled her eyes heavenwards and turned to see what the problem was this time. Amber was balancing on one foot in the mangrove swamp and holding the other leg clear of the green, stinking water.

'What?' said Li.

Amber pointed a shaking finger at the back of her knee. A very large leech was hanging there. It was olive green in colour, with lines of small, black dots along its length. The body below the mouth was distended into the shape of a pear, the rounded end full of blood. The leech was pulsing slightly and its glistening skin was streaked with Amber's blood, which was also dripping steadily into the swamp water.

'That's going to attract more of them,' observed Li, pointing to the pink tinged water.

Amber flinched, then turned and scrambled up the gnarled root of a mangrove tree until she could perch clear of the water. Li swung herself up beside Amber with one, easy motion, then bent to look at the leech.