But something stopped him.

One of the men no longer had his Kalashnikov slung round his back; he was gripping it firmly and using it to prod the struggling Halima towards the truck. In an instant, Ben realized the truth of his situation: there were four of them, at least three of them heavily armed, and only one of him. And he'd never fired a gun in his life. He stopped in his tracks. Perhaps he should just slip away, do what his dad had told him and try and make that phone call. Suliman was diverted, and now would be a good time.

Then Halima screamed again, a terrified sound, and Ben realized he couldn't just leave her. He had to do something to help, and it would have to be something more subtle than just charging in there, inexpertly wielding a handgun. An idea formed in his head. It would be dangerous, but he could think of no other option.

Calmly he switched the safety catch on again, then tucked the gun into his combats, pulling his baggy T-shirt over the top to disguise its presence. Halima was almost at the Land Rover now, and Suliman was making his way towards the front passenger seat. Ben took a deep breath, then ran towards them.

'Hey!' he shouted. 'What are you doing? Leave her alone!'

Suliman, the three men and Halima all spun round to see Ben hurtling towards them, his arms waving in the air. He saw the girl shake her head, her desperation suddenly replaced by an urgent if silent warning for Ben to get out of there. The men looked less fearful; they sneered at each other, and then two of them raised their rifles in his direction. Ben skidded to a halt, feigning surprise, then spun round as though looking for an escape route. 'Put your hands on your head, Ben' – he heard Suliman's quiet, intent voice – 'and walk towards us, slowly.'

Ben did as he was told. As he approached them, one of the men walked towards him and then followed him from behind, prodding the AK-47 into his back. He carried on walking towards Halima.

'Empty your bag,' Suliman instructed. Ben did as he was told, silently grateful that he had hidden the gun under his clothes. The bag was empty.

'Get into the back seat,' Suliman whispered. Ben felt the gun jab sharply into his back, and he stumbled forward. Halima was already being bundled into the back, and Ben scrambled in, taking his place next to her.

'You should not have come!' she whispered.

'I had to,' Ben breathed. 'I'll explain later.'

'Quiet!' Suliman was in the passenger seat now, directly in front of Ben, and two of his men had taken their places in the driving seat and the third seat in the middle. From the front, Ben could smell stale sweat and alcohol – someone had been drinking. He glanced out of the side window to see the remaining man step back down from Halima's open door, slamming it shut behind him. The engine started and the Land Rover skidded slightly as it set off and made its way to the edge of the village.

'Where are we going?' Ben asked tensely, watching Suliman's expressionless face jolting in the rear-view mirror on account of the bumpy road and poor vehicle suspension.

The men in the front remained silent.

'I know there's something down the mine,' he insisted, ignoring the hiss that came from Halima. 'My father fell ill this morning.'

Suliman smiled. 'That is good,' he said softly. 'It means there is one less of you to deal with.'

Ben felt a surge of anger welling up in him. The vehicle was moving quickly. There was no way they could safely jump out, even if they could have coordinated such an action without raising the suspicions of their captors; but the outskirts of the village had already melted away, and a mile after they left the last dwelling place, Ben realized he had to act now or not at all. Slowly, and as inconspicuously as he could, Ben reached his hand under his T-shirt and removed the gun from his jeans. The safety catch clicked softly as he undid it, but the sound was more than overwhelmed by the clattering of the Land Rover over the poor road. Halima's eyes widened slightly when she saw what he was doing, but she managed to suppress the gasp that rose involuntarily to her lips.

Now the gun was out, he had to move swiftly. He held it up and placed it directly to the back of Suliman's skull. 'In case you were wondering,' he said firmly, 'the thing you can feel is an automatic handgun. Tell the driver to slow down or I'll shoot the three of you – starting with you.' The aggressive words felt uncomfortable in his mouth, but he knew he had to keep up the pretence of confidence. Their lives depended on it.

Instantly the man in the middle started to raise the Kalashnikov that was resting on his lap. 'Tell him to put it down or I'll shoot,' Ben screamed.

Suliman shouted at his man in Kikongo, and he abruptly dropped the rifle. The driver looked nervously at Suliman, maintaining his speed and waiting for his instructions.

'Halima.' Ben spoke without turning his head to look at her. 'If he tells the driver to do anything except stop the car, tell me.'

Suliman's eyes narrowed, and he spoke shortly to the driver, who instantly slammed on the brakes. Everyone in the truck jolted violently forwards as the vehicle skidded through a right angle; Ben found himself hurtling forwards and to the side, his gun arm slipping past Suliman's head and into the space between Suliman and the man in the middle. Instantly Suliman's hand flew up and grabbed Ben's arm firmly.

Bang! The shock of his touch made Ben squeeze the trigger, and a deafening sound numbed their eardrums as the bullet ripped into the dashboard. But Suliman kept his grasp, squeezing hard and painfully while his accomplice slowly peeled Ben's struggling fingers from around the gun grip. The man caught it before it fell to the floor.

By now the vehicle was at a standstill, but pointing towards the side of the road. Suliman spoke briefly to the man sitting next to him, then let Ben's arm go and took the handgun from his accomplice before opening the door, climbing out of the front and getting into the back next to Ben. He held the gun firmly against his abdomen, then gave the driver a muttered instruction. The Land Rover started moving again, straightening itself out before continuing along the road.

'You won't get away with this,' Ben told him. 'People know I'm here.'

Suliman ignored him.

'You need to listen to me,' Ben persisted. 'There's a virus down there. That's what's killing everyone. If you let it spread, millions of people could-'

'Speak again, Mr Ben,' Suliman interrupted him with a growl, 'and it will go very badly for you.'

They drove for twenty minutes. Ben stared ahead of him, his face fixed in an expression of the deepest contempt, and even though he didn't dare turn to look at her, he could sense that Halima was doing the same. He could sense Suliman too; he was close enough for him to feel the warmth emanating from his skin, and he could smell the sweat on his clothes. Ben was sweating as well, from a horrible mixture of humidity and fear. But most of all, he could feel the barrel of the gun bruising between his ribs. He did his best not to think about it, trying instead to come up with a way to get out of this. There had to be something he could do.

He could think of nothing.

One of the men in the front pulled a pewter hipflask from his pocket and drank deeply from it. He offered it to the driver, who shook his head in annoyance. Around them the state of the road worsened, forcing the driver to reduce his speed somewhat, and the vegetation grew thicker: tall rubber trees started to line the road, forming an impenetrable wall of rainforest. There were no other cars. It all looked deeply inhospitable. At one stage the car slowed down as it negotiated a rickety wooden bridge crossing a wide river. The river itself was not very full – just a stretch of muddy-looking water slinking its way underneath them. Ordinarily, the treacherous bridge would have made Ben uneasy; at the moment, however, his mind was on other things.