'Of course,' the South African stated. 'Our mine manager controls all the transport in the village, and we have stopped any mail or deliveries from coming in or out. But I'm afraid there is an unforeseen problem.'

'What is that?'

'The workforce. They are dying more quickly than we anticipated. We don't have enough men or boys to work the mine.'

'Then you will need to bring in more personnel. Where is the nearest village?'

'Half a day's drive away.'

'We must import more workers from there. But we must keep it a secret, what we're doing.'

Suddenly one of the other white men spoke. 'If it's secrecy you want,' he observed, 'then I'm afraid it is already compromised.'

'What do you mean?'

'I mean the scientist. He will return to the outside world soon enough; and what if he suspects what we suspect about the deaths among the mine-workers and their families?'

The South African smiled blandly. 'His work will be done in a matter of days,' he observed before standing up and looking out of the window into a neat courtyard below. 'Unfortunately he has his son with him.' The men around him looked troubled. 'He's an unprepossessing kid – I don't think he will cause us any trouble. But I caught him speaking to one of the villagers who works in our offices.'

'She told him the rumours?' Nkomo asked.

'I don't know. But it's OK – I have arranged for them to travel to Udok earlier than expected. That way, we don't risk anybody else filling their heads with ideas. And of course, people succumb to all sorts of things in that part of the Congo.'

He turned round and gave everyone in the room a knowing look, which they returned in unified silence.

'Then I suggest' – Nkomo spoke in a monotone voice – 'that once the scientist has done his job, he and his son are considered entirely dispensable.'

Everyone in the room nodded their heads slowly.

'Good,' Nkomo continued smoothly. 'Then I think that just about concludes our business. Thank you for keeping us informed, Mr Kruger. You have been most helpful.'

The Cessna started losing height.

Since Abele's mysterious warning, there had been almost no conversation in the cabin, and Ben had resorted to gazing aimlessly out of the window and watching the vastness of Africa pass beneath him. From that height it was difficult to make out the landscape over which they were flying, but as they prepared for landing, he found himself able to make out more distinct features: the thick canopy of jungle, the occasional weather-beaten road, the river. They called Africa the dark continent, but all Ben could see was a riot of colour.

The landing was a lot less smooth than the one they had experienced in Kinshasa Airport earlier that day – Ben was pleased he had heeded the instruction of the smiling pilot to strap himself in. Finally, though, the vigorously jolting plane came to a stop, the doors were opened and the passengers stepped out into the oppressively humid outside. Ben felt his clothes cling immediately to his skin as Abele pulled down their luggage and carried it to the side of the runway. There was little to distinguish this airfield from any other patch of cracked earth – Ben squinted as he looked around at the unfamiliar, slightly hostile surroundings. Nothing. No buildings, no shelter: just an expanse of earth covered with low brush and brown dust. Abele spoke to the pilot in an African dialect: he shook his head and then walked over to Ben and his father, hand outstretched and grin still intact, revealing several misshapen, yellow teeth interspersed with four or five gaps.

'You are not coming to the village with us?' Ben's dad asked in that loud, slow voice people use when addressing someone who doesn't speak their language.

If anything, the pilot's grin became wider as he shook his head and waved a finger in front of him, before turning and clambering back into the cockpit. The Cessna was gone as quickly as it had arrived, leaving the three of them alone with their bags and an uncomfortable silence, staring as the plane disappeared into the skies.

By the side of the road was a small copse of palm trees which cast a long shadow in the afternoon sun. The trio took shelter in the shade as Ben and his dad waited for Abele to tell them how they were to be transported from here. 'They send someone to collect us,' he murmured, before turning his back on his two English companions and gazing out into the distance. Ben peered around him. The mid-afternoon sun was causing a wavy haze of heat in the near distance, making it difficult for him to focus on any one thing, even with the expensive Polaroid shades his mum had insisted on buying for him. In one direction, though – a mile away, perhaps less, perhaps more – he saw something moving across the horizon. It was a crowd of animals, travelling at some speed, though he could not make out what they were.

Suddenly he jumped as he heard Abele's voice right next to him. 'Olive baboon,' he noted, a look of distaste in his face.

'Are they dangerous?' Ben asked, unable to take his eyes off the troop.

Abele shrugged. 'Not wise to get too close. But more nuisance than dangerous. They steal food.'

Just then their attention was distracted from the baboons by the quivering, hazy sight of a car appearing in the distance. Abele raised his arm in the air and stood by the side of the road while Ben and his father waited wordlessly behind him. It took the car longer to reach them than Ben would have expected – it was a beaten-up old thing, trundling slowly along. Finally, though, it pulled up at a short distance – perhaps ten metres – from the trio, who were eagerly awaiting its arrival. The driver switched off the noisy engine, opened his door and started walking towards them. The smile on his face was perhaps broader even than that of the pilot who had just left them, though he walked with a curious posture, his hands held firmly behind his back. Noting the presence of two white men, he spoke in broken English. 'You want lift?'

From the corner of his eye, Ben saw Abele's brow furrow, and in that split second he himself realized that what this stranger had just said to them was odd. If he'd been sent to pick them up, why would he be asking them if they wanted a lift? He took an involuntary step backwards, but it was too late. He froze as the man let the smile fall from his face and pulled his hands from behind his back to reveal a dull, grey handgun.

Nobody moved. Ben felt a drop of sweat drip down the right-hand side of his face, though whether that was a result of the heat or the sudden fear that was like a shock through his body, he couldn't tell. He stared at the man who had them at gunpoint. His lip was curled now, and there was a look of flat menace in his eyes that suggested to Ben he would not hesitate to use his weapon if they didn't do exactly what he said – or even if they did.

Their attacker twitched the gun down towards the bags. 'Empty them,' he commanded.

Ben and his father glanced at Abele, who nodded at them. Ben was the first to bend down to his bag. 'Slow!' the attacker barked, the word spoken with such sharp urgency that for a millisecond he thought it was the sound of the gun firing. Struggling to keep control of himself, Ben slowed his movements down, unzipped his luggage and then started to upturn it.

But before he could spill its contents onto the dusty ground, there was movement.

The attacker had stepped closer to Abele who, with a quickness that Ben would never have expected of him, shot out his hand and grabbed the arm with which their attacker was holding the gun. There was a brief struggle, and suddenly the gun went off. The bang rang in Ben's ears and caused a host of unfamiliar birds to rise as one from their hiding places in the low brush. Ben and his father watched in frozen horror as the two men struggled to get control of the weapon. They were an evenly matched pair – both strong, both desperate – but eventually the attacker managed to strike Abele a vicious blow across the side of the face. Abele's head twisted round and he fell with a heavy thud to his knees as the attacker took a couple of steps backwards and aimed the gun directly at Abele's face.