'Slaves!'

'Sure. The Tuareg used to go raiding across the Niger Bend to bring back slaves.'

'Is there still slavery?'

'Theoretically – no. But I wouldn't bet on it. A few years ago a British novelist bought a slave in Timbouctou just to prove that it could be done. Then he set the man free which was a damnfool thing to do.' He saw my frown. 'He had no land, so he couldn't grow anything; he had no money so he couldn't buy anything – so what was the poor bastard to do? He went back to his old master.'

'But slavery!'

'Don't get the wrong idea,' said Byrne. 'It's not what you think and they don't do too badly.' He smiled. 'No whips, or anything like that. Here, in the Air, they grow millet and cultivate the date palms on a share-cropping basis. Theoretically they get a fifth of the crop but a smart guy can get as much as half.'

Byrne seemed well-known and popular in Iferouane. He talked gravely with the village elders, chaffed the young women, and distributed sweets and other largess among the children. We stayed there a day, then pushed on south over rougher country until we arrived at Timia and Byrne's home.

Ever since we had left Fort Flatters Billson had avoided me. He couldn't help being close in the truck but he didn't talk and, out of the truck, he kept away from me. I suppose I had not hidden my contempt of him and, naturally enough, he didn't like it. I had penetrated his thick skin and wounded whatever amour propre he had, so he resented me. I noticed that he talked a lot with Byrne during this time and that Byrne appeared to show interest in what he was saying. But Byrne said nothing to me at the time.

Byrne was unTuareg enough to have built himself a small house on the slopes of what passed for a pleasantly-wooded valley in the Air. The Tuareg in the area lived, not in leather tents as they did in the desert to the north, but in reed huts, cleverly made with dismountable panels so that they could be collapsed for loading on the back of a pack camel. But Byrne had built a house – a minimal house, it is true, with not much in the way of walls – but a house with rooms. A permanent dwelling and, as such, foreign to the Tuareg.

We arrived there late and in darkness and I didn't see much that night because we ate and slept almost immediately. But next morning, Byrne showed me around his kingdom. Close by there was something which, had it been permanent, would have been called a village and Byrne talked to a man whom he told me was Hamiada, Mokhtar's brother. Hamiada was tall, even for a Targui, and his skin, what little I could see of it above his veil, was almost as white as my own.

Byrne said to me, 'Most of the herd's grazing out towards Telouess – about twenty kilometres away. I'm going out there tomorrow. Like to come?'

'I'd like that,' I said. 'But what about Billson?' Billson was not with us; when we had left that morning he was still asleep.

Byrne looked troubled. 'I want to talk to you about him -but later. Now I want to show you something.'

Hamiada had gone away but he returned a few -minutes later leading a camel It was one of the biggest beasts I had seen and looked to be about ten feet high at the hump, although it could hardly have been that. It was of a colour I had never seen before, a peculiar smokey-grey. Byrne said, This is my beauty – the cream of my herd. Her name is Yendjelan.'

He spoke with such obvious pride that I felt I had to echo it even though I was no expert on the finer points of camel-breeding. 'She's a very fine animal,' I said. 'A racing camel?'

He chuckled. 'There's no such thing. She's a Mehari – a riding camel.'

'I thought they raced.'

'Camels don't run – not unless they're urged. And if they run too far they drop dead. Fragile animals. When you come with me tomorrow you'll be riding one. Not Yendjelan, investigation. The weather was good – no sandstorms.'

'Obsessionally thorough.'

'Yeah,' said Byrne. 'But thorough all the same. Now, when Peter Billson went down it would be likely to be to the north of Agadez, and one thing's for sure – it wasn't in the Air. There are too many people around here and the plane would have been found. The same applies anywhere north of the Ahaggar. If it went down there it would have been found by some Chaamba bedouin.'

'So that leaves the Ahaggar and you're certain it's not there. You're talking yourself into a corner.'

He said, 'When the French were getting ready to blow that atom bomb at Arak they lost three planes in the Ahaggar. I've told you about one of them. They gave the Ahaggar a real going-over, both from the air and on the ground. They found three planes which was all they expected to find. I'm pretty sure that if Billson's plane had been there the French would have found it.'

'Perhaps they did,' I said. 'And didn't bother to mention it.'

Byrne disagreed. 'It would have made big news. You don't suppose Billson was the only record-breaking airman lost in the Sahara, do you? There was a guy called Lancaster went down in 1933 south of Reggan in the Tanezrouft. He wasn't found until 1962 and it made the headlines.' I worked it out. 'Twenty-nine years.'

'He was still with the plane, and he left a diary,' said Byrne. 'It made bad reading. Paul knows all about Lancaster; he knows how long a crashed plane can remain undetected here. That's why he thinks he can still find his father.'

'This place where Lancaster crashed – where is it?'

'In the Tanezrouft, about 200 kilometres south of Reggan. It's hell country – reg, that's gravel plain for as far and farther than you can see. I know a bit of what happened to Lancaster because I read about it back in '62 and Paul has refreshed my memory. Lancaster was flying a light plane and 'put down at Reggan to refuel. He took oft7, got into a sandstorm and lost direction; he flew east damn near as far as In Salah before he put down at Aoulef to find out where he was. He'd intended to fly to Gao on the Niger Bend and that was due south, but he's used up too much fuel so he went back to Reggan. He left next day and after a while his engine quit. So he crashed.'

'Didn't they search for him?'

'Sure they did – by air and ground. I don't know how good their air search was back in 1933, but they did their best. Trouble was they were looking mostly in the wrong place, towards Gao. Anyway, he had two gallons of water and no more, because he had an air-cooled engine. He died eight days later, and was found twenty-nine years later. That's the story of Lancaster.'

'Who found him?'

'A routine French patrol working out of Bidon Cinq. What the hell they were doing in the Tanezrouft I don't know. Probably on a vehicle-testing kick – I can think of no other reason for going into that hell hole.'

'All right,' I said. 'You've made a point. So Peter Billson and his plane can still be in the desert. Are you proposing that we go look for it in this place – the Tanezrouft?'

'Not goddamn likely,' said Byrne. 'I think it possible that Billson went off course. When he disappeared there was a search but, just like Lancaster, he wasn't found because they weren't looking in the right place.'

'And you know the right place, I suppose.'

'No, but think of this. Lancaster's place was found by the French. For all we know it might have been seen much earlier by, say, some Hartani or even a Targui. But why would they want to report it? It would mean nothing to them. Don't forget, this plane crashed only three years after the final battle between the French and the Tuareg when the French got the upper hand at last. The Tuareg felt they didn't owe the French a goddamn thing. Sure, if they'd found Lancaster alive they'd have brought him out, but they wouldn't care much about a dead guy in a dead plane.'

'All right,' I said. 'Spit it out. What are you getting at?' Byrne said, 'Would you put up, say, five camels to help find Paul's old man?'