'I hear ya,' Sam whispered. 'But how?'

Purna was silent for a moment, her eyes restless as she took note of the terrain ahead and their available resources. Eventually she said, 'I've got an idea.'

'Make it a good one,' replied Logan.

She outlined her plan to them, pointing out the landmarks she was referring to. When she had finished Logan laughed quietly. It was an incredulous laugh rather than a happy one.

'You're fucking crazy, you know that?'

A brief smile fluttered at her lips. 'That's why you love me.' She tapped Logan's backpack. 'Lucky we brought plenty of ammo with us.' After a couple of deep breaths she said, 'Ready?'

'No,' said Logan. 'But let's do it anyway.'

'OK. On the count of three. One. Two. Three!'

Readying their weapons, they broke cover, each of them running as fast as they could. Purna and Logan to the right, Sam to the left, like a SWAT team spreading out to cover the area. They were halfway to each of their individual destinations when they were spotted. Sam, the pounding of his heart filling his ears, was aware of heads turning in his direction, shapes peeling away from the crush of semi-naked bodies crowding around the trees at the far end of the village and lurching towards him. When several of the infected let out blood-curdling shrieks in unison, prior to breaking into shambling, long-legged sprints, the shock was almost enough to make him lose his footing. A jolt went through his body, powerful as electricity, and he felt himself stumble, his right knee crumpling at the sudden unexpected weight. No, he told himself, and the sheer terror of what would happen to him if he went down was enough to keep him going. He turned and let off a few shots, felling the most rapidly advancing of the zombies, before darting between two huts. Just beyond them was the tree Purna had pointed out to him, and Sam saw immediately that she had chosen well. Swinging the rifle over his shoulder on its adjustable strap, he leaped at the lowest branches of the tree and began to haul himself up. He found his hand-holds and lifted his right leg to a higher branch, and was just about to lift his left foot too when it was seized from below. He looked down to see a woman, her eyes glaring and yellow, her face demonic with rage, clutching his blood-stained Reebok in both hands. Then he felt pain as her head darted forward and she sank her teeth right through his jeans and into his calf.

'Fuck!' he yelled, the bright white shock of the pain enough to give him a surge of adrenalin. He wrenched his left leg upwards with such force that his foot popped clean out of its shoe, leaving it clutched in the zombie's hands. The zombie regarded the empty shoe almost comically for a second, then allowed it to drop to the ground. By the time she raised her head and clawed up towards Sam, he was out of her reach.

He found a branch wide enough and strong enough to take his weight and lay across it for a moment, leaning back on his backpack, panting and shaking. Below him, through a shifting canopy of leaves, he could see zombies already congregating, snarling in what he fancied was frustration, their bloodied fingers scrabbling ineffectually at the tree trunk.

He might have lost a shoe, but at least he hadn't lost his gun or his pack full of ammo or, indeed, his life. His calf where he'd been bitten was stinging like fuck, though, enough to make him feel ill and faint. He wrapped his arms around the branch he was draped across and clung on desperately, fearful for a moment that he might pass out and plunge to the ground below. His forehead was oozing sweat and his heart was like muffled but persistent thunder in his ears. It took several seconds before he realized that someone was shouting his name.

He looked up groggily. At first his vision was nothing but a confusion of waving leaves and blinding flashes of sunlight. The sound penetrated the fug in his mind, enabled him to get his bearings, and eventually he shuffled upright and through a gap in the branches saw Logan sitting high up in his own tree about thirty metres away, behind a bunch of huts on the far side of the clearing.

'Hey!' Sam shouted, his voice thick and a little slurred.

'Fuck, man,' Logan yelled back, sounding pissed off, 'what you been doing? Taking a nap?'

'Kinda,' shouted Sam. 'I got bit. Think I phased out for a moment.'

'You OK?' shouted Purna, the direction of her voice enabling Sam to pinpoint her half way up a tree forty metres to Logan's left.

'I'll live,' replied Sam, and then almost laughed at the irony of his statement.

'Yeah, but will the poor bastard who bit you?' shouted Logan. 'Oh, hang on. I forgot. That's something he doesn't have to worry about.'

'It wasn't a he, it was a she,' shouted Sam. 'And she took my fucking shoe.'

'I'm jealous,' Logan replied. 'What is the secret of your success with the ladies, man?'

'I guess you either got it or you ain't,' Sam yelled back.

Their loud exchange had at least caused the survivors at the far end of the village to stop bickering. Sam imagined them all perched up in the branches of their trees, shocked into silence at this unexpected intrusion into their village. One thing they ought to be grateful for, however, was the fact that the majority of the infected, perhaps realizing that their prey was inaccessible for now, were drifting towards the new arrivals, presumably in the hope of easier pickings. If so, then they were going to be disappointed if zombies could be disappointed, that was.

'OK, let's do this,' Purna shouted from across the clearing. 'You ready, Sam?'

Sam unslung his rifle, raised it to his shoulder and pointed it down at the ground. 'Ready.'

'Ladies and gentlemen,' Logan announced loudly, 'we are just about to make a hell of a fucking noise. I apologize for any inconvenience that this may cause.'

Then they started firing.

'Operation Fish in a Barrel' Purna had called it, a name that was nothing but apt. Sam felt almost guilty as he sat in his tree, firing down at the milling hordes below. Oblivious to fear and danger, the infected didn't run or seek cover; they simply stood there, allowing themselves to be picked off. For over five minutes, Sam, Purna and Logan kept firing and reloading, pumping round after round into the hungry dead, shattering skulls and destroying brains with the same clinical determination they might show if they were eradicating a nest of ants.

By the time it was over, the ground beneath Sam's tree was a thick lake of blood, a swamp of pulped and fallen flesh. The stink that rose from it made him feel sick, and already he was wondering how he could possibly avoid having to wade through it when he climbed down. After so much activity the gun was hot in his hands and the shockwaves of the hundreds of rounds he had fired rippled through his body like a never-ending echo. He felt his hearing had gone into trauma, his jaw ached from having been clenched so tightly, and the double pulse in his temples seemed to prompt an answering beat from the bite-wound in his calf.

Aside from the throbbing of his own body, for several minutes after the shooting was over Sam experienced nothing but a deep, almost profound silence. He suspected that, like him, Purna and Logan were sitting quietly, alone with their thoughts, perhaps trying to come to terms with the oddly heightened reality of what they had just done, or attempting to make sense of the conflicting emotions of exhilaration and self-loathing battling for supremacy in their heads. Sam felt enervated, but at the same time so alert it was like a caffeine buzz. He felt heavy and weightless, centred and scattered, light and dark. Time seemed meaningless, and at the same time he was almost achingly aware of every passing second. He closed his eyes for a moment, and when he opened them again it felt like the world had changed.

At last, slowly, he climbed down from the tree. When he reached the lowest branch, he shimmied along until it started to bend, and then he jumped. Despite clearing the base of the tree by a good five metres, he still landed at the very edge of the killing ground, his shoeless foot landing in blood that had the consistency of cold, partly set jelly. Grimacing, he trudged out on to the dusty main street, leaving a trail of red footprints behind him.

As if by mutual consent, Purna and Logan emerged from between huts on the other side of the street at exactly the same moment and they all walked towards each other, like outlaws meeting for a noon showdown. No one said anything, though the looks that passed between them seemed to convey how they were feeling far more eloquently than words. As one they turned and walked towards the cluster of trees at the far end of the village, and as they got closer the survivors began to drop to the ground, one by one, like strange fruit.

Most prominent among them was a man with long matted hair, whose dark-skinned body was painted in swirling red and white shapes. He wore a crocodile-skin cape and when he walked the bone ornamentation adorning his wrists, ankles and neck jangled ominously. Showing no fear, he marched up to the three visitors to his village, drawing a ceremonial dagger from his belt as he did so. Purna tensed and half raised her gun, but the man halted a couple of metres from them, placed the dagger on his palm with the blade pointing towards his own chest and dropped to his knees. He tilted his upper body forward as though in supplication, his forehead all but touching the dusty ground, and stretched out his right hand, offering them the dagger.

Logan looked at Purna. 'I think that means he likes you,' he said.

Chapter 16.

THE LIVING DEAD GIRL.

'KORITOIA-OPE.'

Purna slowly repeated the name and the witch doctor nodded delightedly. Despite his fearsome appearance he had been an amiable enough companion. They had been walking for several hours now, heading ever upwards. For the first three hours they had been hacking their way through thick jungle, but now they had risen beyond the treeline and were ascending the dusty, upward-sloping trail of a jagged-peaked mountain. Sam couldn't decide whether he preferred struggling through dense vegetation, where at least the ground was level and they were sheltered from the sun, or toiling uphill, where they were unencumbered by trailing vines and ankle-entangling plants, but where they had to contend with the mercilessly beating sun.

At least they had set off at dawn, which meant that the sun had not been at its height. Even so, long before they reached their destination sweat was rolling down Sam's face and his freshly laundered T-shirt was plastered to his body. The hiking boots that West had lent him (he hadn't even bothered trying to locate his lost Reebok in the charnel pit of zombie remains at the bottom of the tree) were pinching a little, but he could cope with that. And at least, for once, he didn't stink of zombie blood which was always a bonus.

After making the acquaintance of the surviving Kuruni villagers yesterday, Purna, Sam and Logan had persuaded them through a combination of gestures and basic vocabulary to accompany them back through the jungle to where Mowen was waiting with the jeep. After getting over his initial surprise, Mowen had spoken to the witch doctor and, although their two tribal languages had not been entirely compatible, had at least been able to make him understand why the four of them had come to the village and what it was they needed. Perhaps in exchange for saving their lives, or simply because he had witnessed first-hand how frighteningly out of control the virus had become, the witch doctor Koritoia-Ope had eventually agreed to lead his people to the research centre and allow West to take blood samples from them in an effort to develop a vaccine. Furthermore he had agreed to take a party up to the sacred Kuruni burial site early the following morning, so they could get a sample of the stable form of the virus.

Sam had never before appreciated the sheer bliss to be found in what he had always thought of as the simple things in life taking a shower, putting on clean clothes, eating a good meal, sleeping in a comfortable bed. It might have been only twenty-four hours since the outbreak of the virus had reached pandemic proportions, but by the time they arrived back at the research centre and he was finally able to enjoy a bit of downtime. He felt like he'd been fighting and running for days.

It was agreed that he and Purna would accompany Koritoia-Ope to the burial site at dawn the next day, while Logan and Mowen would monitor proceedings at the research centre and keep Ryder White up to date with developments. At first Logan had offered to go with Purna to give Sam more time to get over his latest zombie bite, but Sam had insisted that he'd rather be doing something than hanging around and besides, although he didn't say so, he was pretty sure that Logan's knee would not be able to stand up to what Mowen had told them would be almost a full day's hike there and back over pretty tough terrain.

It was obvious that the same thought was in the back of Logan's mind too. Shrugging he had said, 'Well, if you really want to go, man, far be it from me to spoil your fun. I'm more than happy to hang around here all day. Hanging around is what I'm good at. And if I get bored I can always pass the doc a test tube or something.'

By the time they finally arrived at the burial site, Sam was beginning to regret telling Logan that he'd rather be doing something than nothing. It was still only 10 a.m., but the reflection of the sun on the pale ground was enough to make him wish he'd thought to ask Mowen if he could borrow his shades, and every outcrop of rock he touched with his hands or brushed against with his leg was red hot. He was relieved when Koritoia-Ope stopped and pointed at a carved stone arch jutting from the mouth of the cave, which was stoppered by a boulder just as tall and at least three times as wide as Sam himself.

The witch doctor unleashed a stream of words, nodding and pointing to emphasize what he was saying.

Purna nodded back at him. 'I think this is it,' she muttered to Sam.

Sam shrugged off his backpack and delved inside, grateful that he'd heeded Mowen's advice to bring plenty of water. Finding a full litre bottle he unscrewed the cap, gulped several mouthfuls and poured some over his head. He was almost surprised when the water didn't sizzle and evaporate on contact with his skin.

'Don't waste it,' said Purna. 'We've got the return journey to make yet, remember.'

'Yeah, I was thinking about that, and I figure I might catch the bus back,' said Sam.

Koritoia-Ope waited patiently while Sam and Purna rehydrated. Purna offered him the water bottle, but he simply looked at it with a mixture of suspicion, perplexity and contempt before shaking his head. Certainly he didn't seem to be affected by the heat; his skin appeared as dry and leathery now as when they had started out. Walking up to the boulder plugging the cave entrance, he made a pushing gesture with his hands.

'Great,' said Sam. 'Manual labour. Just what we need.'

'If you don't stop moaning I may be forced to break your nose,' Purna said mildly.

Sam laughed. 'Man, I bet you are one high-maintenance chick.'

'You better believe it.'

Shrugging off their backpacks and laying their guns carefully on top of them, Sam and Purna walked forward and placed their hands on the boulder. Once again the witch doctor made a pushing gesture.

'I think we get the general idea,' muttered Purna.

Gritting their teeth, Sam and Purna pushed as hard as they could. At first the rock seemed immovable, but eventually it shifted a little before settling again.

'I think we need to rock it,' Purna said.

'I been rocking it all my life,' replied Sam.

They tried again, coordinating their movements, giving the boulder a series of shoves rather than trying to shift it with one sustained effort. Sure enough, after ten seconds or so, the boulder began to rock backwards and forwards, just a little at first, and then more and more as it gained momentum. Finally, face sheened with sweat, Purna said, 'One more big one ... Now!'

The two of them grunted and heaved, and the rock rolled aside before toppling over with a crash.

Released from the cave, a wave of air rolled out and over them, and although they welcomed its chilliness, Purna and Sam wrinkled their noses at its fetid odour. They turned to the witch doctor, who was chattering excitedly. Purna pointed at the dark cave opening. 'We can go in?' she asked.

Even though they were unsure whether Koritoia-Ope had understood the question, they took his answering nod as confirmation. Retrieving their guns and backpacks, they ventured inside, Sam first, Purna just behind him and the witch doctor bringing up the rear.

The interior of the cave was dank and cold and dark, the ground uneven. Indeed, immediately upon entering, there was a series of natural steps, which all but cut off the spill of daylight from outside and resulted in the floor level quickly dropping by several metres. Purna took a flashlight from her backpack and shone it around. The passage ahead was narrow and winding, the walls rising up from it in a curve. It made Sam think of that old story about Jonah in the belly of the whale.

'How far?' he asked the witch doctor, but the old man simply waved him on, the jangle of the bone bracelets on his wrist echoing eerily. They ventured forward, wary of stumbling and turning an ankle or worse on the slippery floor.

In fact, it wasn't long before the passage widened out into a huge cavern, the ceiling high above their heads and the walls lined with row upon row of alcoves hacked from the rock. In each of the alcoves had been laid a body, virtually all of which were now nothing more than exposed grey bones and mummified flesh, the bindings they had been lovingly wrapped in having perished to grey scraps as insubstantial as cobwebs.

Looking around, Sam said glumly, 'A couple of years, West said. But these guys look as if they've been dead for centuries.'

Koritoia-Ope, however, was already pushing past them, taking the lead, gesturing towards a black opening on the far side of the cavern. He spoke urgently, nodding all the while.

'This is obviously the oldest cavern,' Purna said. 'I guess once this one was full, the Kuruni had to go deeper. That's where the fresher meat will be.'

'Nice,' said Sam.

They moved on, passing through the valve-like opening on the far side of the cavern into another narrow tunnel. Purna's flashlight beam slithered around the walls, highlighting the gleam of dampness and the black ridged shadows in a startling and somehow primal chiaroscuro.

After another fifty metres or so the tunnel widened into a second vast cavern, the walls of this one too resembling a vast hive for the dead. As Purna had guessed, the bodies were fresher here, as evidenced not only by the sight of them, but also the smell.

Sam felt his gorge rise and swallowed it down with an effort. Taking shallow breaths, he muttered, 'Let's get this done quick. It ain't nice in here.'

'Shh,' Purna said.

'What's up?'

She raised a hand. 'Just be quiet a minute.'

Sam stood still and listened, holding his breath. He could hear the steady drip of water, and something else too. A scratching sound.

'What's that? Rats?'

Purna's flashlight beam danced across to her left. 'It's coming from over there.'

As soon as she began to head in the direction she had indicated, Koritoia-Ope ran across and stepped angrily in front of her, blocking out her flashlight beam, shaking his head and waving his hands.

'What's with him?' said Sam.

Purna halted, looking at the agitated witch doctor thoughtfully, but she didn't retreat. 'There's obviously something he doesn't want us to see.'

'Something alive, from the sound of it,' said Sam.

'Or someone,' she replied.

Koritoia-Ope stepped even closer to her, put his hands on her arms to steer her away. Purna shrugged him off.

'Get off me. What are you hiding?'

The witch doctor jabbered at her, his eyes flashing, his lips curling back to reveal teeth sharpened to points.

Stepping back from him, Purna raised her flashlight and shone it around his body on to the opposite wall. Between two rows of alcoves was an arched opening sealed not only by a stone slab but a boulder almost as big as the one at the mouth of the cave, which had been wedged up against the slab to keep it firmly in place.

'Hey!' Purna shouted, her voice echoing around the walls. 'Anyone in there?'

There was a renewed flurry of scratching.

'There is someone!' Purna said.

'Unless it's some kind of animal,' replied Sam.

'Knock if you can hear me,' Purna shouted.

There was a pause, and then a bout of weak but unmistakeable pounding from the other side of the slab.