'This is the most important task I have asked you to perform, given to me by Osama's personal representative in London, the Preacher. So, it is very, very important that you succeed.'

'Of course. I know exactly what I'm doing. There is only one problem. Captain Abu Salim and his two Sergeants will certainly be in the line of fire: is this acceptable?'

'As you say, things happen all the time in the border area. Salim is a nothing. He sees things entirely differently from you and me. With Osama's blessing on you, your success is assured.' Noon: the sun high in the sky, with a wind that stirred the sand. On leaving the city, they joined a convoy of civilian trucks, many of them garishly decorated, military or police vehicles constantly overtaking each of them on the short stretch up to the Khyber Pass. Some time before they got there, under instructions from Khan, Sergeant Nasser turned off on to a well-worn track.

Salim, seated beside Khan, half turned to Ferguson and Miller. 'Federal law only applies on the main road and ten yards on either side. Elsewhere, tribal laws apply.'

Dak Khan said, 'I call this the wilderness.' They passed a small village of four or five mud houses. Two robed men stood by a well watching them, showing no emotion, staring. 'These people are very poor, they have nothing, so they would kill you if they had the chance.'

'Never mind that,' Salim said. 'Where are we going?'

'About eight miles more.' Dak turned his head and added, 'Our destination is very close to the border.'

It was a barren, undulating plain drifting towards the mountains. Dust rose from the burnt, parched land, and Ferguson, holding a handkerchief to his mouth and coughing, said, 'God in heaven, how can anyone live here?'

Khan was wearing a battered Panama hat and a long cotton scarf around his neck, which he occasionally pulled up to his nose.

'It is the will of Allah, it is all they know, General, and we are here.'

Over to the left, the ground lifted to a hillock on which stood a sizeable two-storeyed house that had been painted white at some time. There was an extended wall of mud bricks around it, and windows with wooden shutters, partially open.

A man in blue-and-white robes stood in the yard beside a well, a bucket in one hand and some goats beside him. He looked, turned quickly, opened the front door and stepped inside. The goats came out on to the hillock, bleating, and two or three rough-looking sheep appeared around the side of the house.

A line of stones on either side marked the track up to the house, and beside the entrance, from what passed as a road, was a thorn tree, burnt black by the sun, a dead monument to a dead world.

As Nasser turned the Sultan into the track, Khan said, 'Stop here by the tree.'

Said stood up at the machine gun and charged it, leaning on the frame, looking up towards the house, and Dak Khan took out his mobile and dialled a number.

He spoke in English. 'It's me. Everything is okay. We want to come up to the house.' He listened and then turned. 'He's afraid of the machine gun; he's not certain of our good faith.' He paused, listening again, then said, 'Okay, if that's the way you want it.'

'What's happening?' Ferguson asked.

'He's suspicious. He wants you to stay here and me to go up to the house to establish my credentials.' He shrugged, 'That's the only way he'll do it, otherwise he says you can go away.'

Ferguson turned to Captain Salim, 'What do you think?'

'Well, as we've come this far, let's humour the man.' He said to Said, 'Swing the machine gun on its pivot to cover the house.' He opened the door and got out, and Khan followed him. 'It's all yours. We'll cover you.'

Dak Khan took off his Panama, wiped his face with the scarf and managed a smile. 'I'm sure everything will be fine.'

He started up the track, and three of the goats came to meet him. Salim, binoculars around his neck, raised them and scanned the house.

'The inside of the place is very dark. No sign of any movement.' He paused. 'Yes, I think there's someone there.'

Dak Khan had reached the house, paused, and the door was opened. As he stepped inside, there was a brief flash of white, and then the door closed again.

'So now we wait,' Ferguson said, and Miller opened the door on his side to get out.

As he did so, a shot was fired, a sharp and peculiar cracking sound that echoed in the desert heat. It caught Sergeant Said in the side of the head, his scarlet turban flying into the air as he was catapulted over the side of the Sultan. Nasser's reflex action was to open the door at his side and attempt to scramble out. Three very quick shots, all making that same peculiar cracking sound, hit him in his neck and back, driving him down to collapse over the body of his comrade.

There were three more quick shots, two smashing the windscreen, flying glass cascading over Abu Salim as he crouched beneath the machine gun, another deflected by armour plating.

There was blood on his face from several cuts, and Ferguson slipped out of the rear seat and joined Miller, crouching behind the Sultan.

'Do you know what that thing is?' Miller demanded.

'Another relic of the Soviets in Afghanistan. A Dragunov automatic sniper rifle. Absolutely deadly with a competent marksman.'

'What in hell do we do?' Ferguson asked.

'Let's try this.' Crouched right down, Salim reached up to the handle of the machine gun, swung it round in the general direction of the house, and gave it a long burst.

Then he scrambled across and found the others. There was another shot from the Dragunov and, as the echoes died away, Salim flattened himself against the ground and peered cautiously round the Sultan to the house.

Ferguson said, 'What the hell is going on?'

The Dragunov fired again, several times, and was joined by another weapon, a different sound. 'An AK47,' Miller said. 'I'd know that anywhere.'

Salim said, 'Help me drop the back flap. I think you'll find I have a surprise for them.'

There was additional ammunition for the machine gun, and flares of one kind and another, but, most important, half-a-dozen rocket-propelled grenades.

'You're familiar with this weapon, Major?' Salim asked Miller.

'Yes, and I can't wait to try it out.'

They crouched together, aided by the fact that the canvas roof covered the back-seat portion of the Sultan. Salim helped him adjust the tube over his right shoulder, Miller straightened and fired. The grenade exploded to the right of the front door. There were flames, and smoke billowed, but there was also another burst from the Dragunov.

'My turn,' Salim said. Chancing it, he stood up, took careful aim, and the grenade went straight through the front door.

They went up the track cautiously and paused a few yards away. The house was a total wreck, half the roof gone, and parts of it were still burning. The first dead man they came to, lying on his back, was the man with the walleye from Khan's house, and it was obvious that the other three were his companions, although damaged so badly that no one could have recognized them.

The rest of the room had suffered badly but, as they stood there, there was a groaning sound from the very back by a door that led to the rear of the house. Legs were sticking out from under a mass of debris and, when Miller and Salim cleared it, they found Dak Khan.

He was soaked in blood, obviously dying, and yet he still spoke, gasping a little. When Abu Salim knelt to check him, Khan grabbed him by the front of his uniform.

'It's all that bastard Atep's fault.'

Salim knelt on one knee. 'Why do you say that?'

'He's the one. Acting on orders from an Al Qaeda man in London. Someone called the Preacher.'

Ferguson said, 'Does he know what he's saying?'