Without hesitation, Purna swung her rifle from her shoulder and pointed it at Koritoia-Ope. 'Step back,' she said.

The witch doctor looked almost incredulously at the gun and started speaking again. Although they didn't know what he was saying, they could tell from his tone that he was pleading with them, trying to make them understand the folly of what they were doing.

'Back off,' Purna said more firmly, jerking the gun to indicate that he should move aside.

Koritoia-Ope looked furious. Clearly he thought she was doing something very foolish indeed. He began to rant at her again, waving his arms.

'I said ... Back. Off.' She jabbed him with the barrel of the gun, forcing him to retreat a few steps.

Koritoia-Ope shook his head and controlled himself with an effort. When he next began to speak he did so quietly and earnestly, clearly trying to appeal to her reason.

'Sam, do you think you can roll that boulder away from the door?' she said.

'I can try,' said Sam. Hesitating, he added, 'You do think we're doing the right thing here, don't you?'

Purna flashed him a disbelieving look. 'Releasing someone who's been sealed behind a wall and left to die? You can't be serious?'

'Yeah, but what if it's like ... a criminal or something? What if it's someone who's done something really bad?'

'That still doesn't mean they deserve this.'

'Or, OK, what if it's a custom or some kind of ritual we're messing with? You know, like the Aztecs? They had that whole Perfect Victim thing going on. Guys who wanted to be sacrificed to the gods, 'cos it was like this great honour.'

The pounding, though weakening now, was still continuing.

'I get the feeling that whoever's in there doesn't really want to be,' Purna said.

'OK,' Sam said, holding up his hands to concede the point. Watched by a horrified Koritoia-Ope, he walked forward and put his shoulder to the rock. Using all his strength, he heaved, and little by little was able to push the boulder away from the door. Without the boulder jamming it in place, the slab was easier to shift. It scraped, centimetre by centimetre, across the rocky ground until there was a gap big enough for someone to slip through.

Still keeping Koritoia-Ope covered with the rifle, Purna handed Sam the flashlight. He shone it into the gap between the slab and the doorframe, and his eyes widened.

'Holy shit!' he said.

Purna glanced at him. 'What do you see?'

'A girl,' said Sam. He held up his free hand in a calming gesture, clearly intended for the girl to see, and said, 'It's OK.'

'A Kuruni girl?' Purna asked.

'Maybe, but she's wearing normal clothes. Western clothes, I mean. She's been tied up and gagged.' Even as he was saying this, Sam was laying the flashlight aside, crouching down and reaching forward through the gap.

'It's OK,' Purna heard him say again, his voice slightly muffled. 'We're here to help. We ain't gonna hurt you.'

Next moment he was backing out of the gap with a young girl in his arms. She looked half-dead, her clothes torn and dirty, her face filthy and tear-streaked, her head lolling.

Gently Sam lay her down on the rock-strewn floor of the cavern and tried to untie the vines securing her wrists.

'Shit,' he said after a moment. 'This is impossible. You got a knife or somethin'?'

'In my backpack,' said Purna, one eye on the girl, one on the witch doctor.

Sam found the knife and returned to the girl. He cut away the gag around her mouth and then the vines securing her wrists and ankles. He winced at the ugly red weals caused by her constraints and hoped that the loss of circulation in her hands and feet hadn't caused her any permanent damage.

'You're OK,' he kept saying, 'you're safe now.'

Although she seemed dazed, the girl nodded.

'You understand what I'm saying?' said Sam, surprised.

'Yes,' whispered the girl.

'What's your name?'

'Yerema.'

'Hi, Yerema. I'm Sam and this here's-'

Before he could say Purna's name, there was a sudden shriek and Koritoia-Ope leaped forward. Taking advantage of Purna's momentary distraction caused by Yerema's confirmation that she could speak English, he shoved the Australian girl aside and snatched up a jagged fist-sized rock from the floor. Still shrieking, he kicked Sam hard in the side of the head with the flat of his foot, stunning him, and raised the rock, clearly intending to smash it down on the girl's head.

He was just about to deliver the first blow when two shots rang out. Koritoia-Ope was hurled forward across the girl's body, ragged bullet holes opening in his back and gushing blood. The rock dropped from his hand and rolled harmlessly away into the darkness. For a few seconds there was silence.

Then Sam groaned and sat up, rubbing his head. A little dazed, he looked at the dead witch doctor sprawled across the terrified girl's body.

'Oh, good work,' he muttered.

'I had no choice,' said Purna tightly.

'You OK?' he asked Yerema.

The girl gave a single jerky nod.

Sam grabbed Koritoia-Ope's arm and hauled him off Yerema's body, then helped her to sit up. Turning his head to look at Purna he said, 'Let's just get that sample and get the hell out of here.'

Chapter 17.

CAGED ANIMALS.

'HEY, YOU'RE BACK! So how'd it go?'

Logan jumped up from his bunk as Sam walked in to the tiny room they were sharing at the research centre. Sam groaned, shrugged off his backpack and dumped it in the corner along with his gun.

'Don't ask,' he said, staggering over to his own bunk and collapsing on to it.

'Already did,' said Logan. 'So come on. Spill the beans.'

Sam's legs were humming with tiredness. He thought that if he closed his eyes he might sleep for a week. 'Well, we got the sample,' he muttered. 'Purna's giving it to West now. That's the good news.'

'Which means there's bad,' said Logan.

'Uh,' Sam grunted.

'"Uh"? What does "uh" mean? I know you've walked a million miles today, but if you don't tell me I'll just keep on asking till it drives you insane.'

Sam groaned again and shuffled halfway upright, folding his pillow to prop up his head. 'That witch doctor guy's dead,' he said.

'Shit! No way, man! What happened?'

'Purna shot him.'

Logan blinked. 'Oh-K. Any particular reason? He look at her funny or somethin'?'

Briefly Sam told Logan what had happened up at the burial site. When he had finished Logan asked, 'So who is this Yerema chick?'

'She was the witch doctor's daughter, if you can believe it,' said Sam. 'Her daddy was the one who sealed her in there.'

'Sounds like a hell of a family argument. She tell you why?'

'Some. Seems she decided she wanted to see the world and get an education, even though her daddy wanted her to stay home, become a wife and mother, follow the traditions, all that shit. They argued about it a lot, I guess till finally she just upped and left.'

'Ran away?'

'I guess so. Anyway, she told us that at first she thought she'd never be able to go back home, that if she did her daddy's vengeance would be terrible. But then once she'd been among "civilized" people for a while, and had seen how reasonable they could be how they listened to you, and how sometimes, if you put over your argument well enough, you could get them to change their mind she started to think that maybe her own people weren't as rigid and primitive as she'd thought, that maybe she could get her daddy to see her point of view, after all.'

'I'm guessing that was a big mistake,' said Logan.

Sam nodded. 'Not only did her daddy not listen to her, but he tried to drive the evil out of her by getting some of the guys in the village to torture and ritually rape her.'

'Jesus,' Logan said. 'That's fucking sick.'

Still nodding, Sam said, 'And the thing was, it looks like that's how all this shit started in the first place.'

'What do you mean?'

'The guys who raped Yerema? They got ill and died. But not only that they came back. They were resurrected as the walking dead. Yerema said at first that her daddy saw this as a sign of forgiveness from the gods. He thought the gods were telling him the guys had been made immortal, and that they'd sent back their bodies so the rest of the village could eat their brains and become immortal too. So a whole lot of brain-eating went on, and a whole lot of people died and came back. Thing was, the Ope family and their close relatives didn't get sick. They contracted the virus, but it didn't change them; they just lived with it. Yerema's daddy thought this was because the gods had cursed them due to Yerema's running away an' all. So to appease them he offered her up as a sacrifice. He locked her in the tomb and left her there to die.'

'And then the plague began to spread all over the island,' said Logan.

'Pretty much. The Kuruni kept themselves to themselves most of the time, but they had occasional contact with the outside world. It must have started with a trader or something; maybe even one of the security guards here picked it up when the Kuruni came to call and took it back into the city with him.'

'Shit,' Logan said. 'Guess the girl must be feeling pretty bad knowing she's the cause of all this.'

Sam's brow wrinkled in a frown. 'It ain't her fault.'

'I know that,' Logan said. 'I just meant, if she hadn't come back to the village ...' His voice tailed off and he smirked. 'Hey, you got the hots for her or something?'

'Give me a break,' Sam muttered. 'She's just a sweet kid is all. She don't deserve all the shit she's had to put up with.'

'Guess none of us do,' said Logan.

'Yeah, well, some of us create our own problems.'

'What's that supposed to mean?'

Sam's frown faded and he waved a hand, as if to dismiss his own comment. 'Nothing, man. I'm just tired. I was thinkin' of me more'n you. All this shit, it's made me realize how much we blame other people for our own fuck-ups. If I ever get out of this I'm really gonna straighten my life out, y'know?'

Logan nodded. 'You and me both, man.'

There was silence between them for a moment, then Sam said, 'So what's been going down here?'

Logan shrugged. 'Nothin' much. West's been analysing blood samples.'

'What about the people we rescued? They OK?'

'Not really.' Logan grimaced. 'West had to lock them up.'

Sam sat upright with a jolt. 'Why'd he do that?'

Logan hesitated, then said, 'Come see for yourself.'

Although Sam really didn't want to get vertical again, he followed Logan through the base until they came to the laboratory. West was there, talking to Purna.

'Where's Yerema?' asked Sam.

Purna turned to look at him. She looked drawn, but she was holding it together pretty well. 'She's resting.'

'OK if I show Sam the patients?' asked Logan.

West waved a hand in a vaguely affirmative gesture. If anything, he looked more worn out than Purna did. 'No problem. But be careful.'

There was a second door on the far side of the laboratory, which until now had always remained closed. Logan punched a code into a keypad on the wall beside the door and the door opened. He led Sam down a short flight of steps and then along a dingy corridor to another door. This one too he opened by punching a number into a keypad.

'Heavy security,' said Sam.

'Yeah, except for the fact that the walls in this place are paper thin,' said Logan, rapping on the wall next to the door and producing a hollow sound that gave the impression it was constructed of nothing more substantial than thick cardboard.

Beyond the second door was a wider corridor, the left wall occupied by four cages, the bars of which stretched from floor to ceiling. Inside the cages was the handful of Kuruni people who had survived the massacre in their village. Although some were worse than others, they all looked in a pretty bad way. Curled up on mattresses on the floor, or slumped listlessly against the far wall, they were sweaty and feverish and hollow-eyed, some tossing and turning and muttering deliriously in their sleep, one or two even tensing and shuddering as if their bodies were being wracked by a series of small seizures.