'Where are they now?'

'Gone to Agadez to fill up with gas. I think they'll be back.'

I thought about it, then said slowly, 'That tells us something. They're not just looking for Billson; they're after anybody who is looking for that bloody plane. Billson's name wasn't on the leaflet, was it?'

'No,' said Byrne shortly.

That does it,' I said. 'It must be the plane.' I put my hand on his arm. 'Luke, you'd better watch it. They put a bullet into Billson on sight. They could do the same to you.' I realized that I had addressed him by his given name for the first time.

He nodded. That's what I thought.'

'Christ, I'm sorry to have got you into this.'

'Make never no mind,' he said. 'I'm not going to stick my head up as a target And you didn't get me into this. I did.'

I said, 'So it's Peter Billson's plane. But why? Why should somebody want to stop us finding it?'

'Don't know.' Byrne fumbled under his djellaba and his hand came out holding a piece of paper. 'First results have started to come in. Maybe we should have just offered one camel; they're reporting every goddamned crashed airplane in the desert. Fifteen claimants so far. Five are duplications -reporting the same plane – so that cuts it down to ten. Six of those I know about myself, including that French plane in Koudia I told you of. That leaves four. Three of those are improbable because they're in areas where any crash should have been seen. That leaves one possible.'

'Where is it?' lip on the Tassili n' Ajjer. Trouble is it's way off Peter Billson's great circle course.'

'How far off?'

'About fifteen degrees on the compass. I know I argued that Billson must have been off course – that's why the search didn't find him. But fifteen degrees is too much.' He accepted a cup of tea.

'So what do we do now?'

'Sit tight and wait for more returns to come in.' He sipped the tea and added as an afterthought, 'And keep out of Kissack's way.'

'Couldn't we do something about him?'

'Like what?'

'Well, couldn't Paul go to the police in Agadez and lay a charge of attempted murder?'

Byrne snorted. 'The first thing they'd ask is why he didn't tell the Algerian authorities. Anyway, the cops here wouldn't be too interested in a crime that happened in Algeria.' He was probably right; I doubted if there'd be any Interpol cooperation in the Sahara. He said, 'I'm tired,' and rolled over and went to sleep in his sudden way.

I beat my brains out wondering why Kissack and Bailly should want to kill anyone searching for an aircraft that had crashed over forty years before. Presently I stopped thinking. I wasn't aware of it. I was asleep, too.

Byrne had brought us some provisions. Millet to be pounded in a mortar and boiled to a thin gruel before having crushed dates added, and flour and salt to make flapjacks. Azelouane went off somewhere and returned with a goat kid which he killed by slitting its throat, so we had fresh meat.

And so we sat tight in the hills, half a day's journey from Timia.

Three days later Byrne went back, leaving early in the morning – and returning the same night. He reported that Kissack was still active. 'He's really scraping the bottom of the barrel,' he said. 'Tassil Oued, Grup-Grup, El Maki – all the little places. But Timia seems to attract him. He knows I live near there. He was in Timia again at midday today.'

'Hell!' I said. 'Be careful.'

He laughed. 'I was standing six feet from him and I was just another Targui. How was he to know different unless someone told him, and my people wouldn't give him a drink of water in the Tanezrouft.' There was a tinge of pride in the way he said 'my people'.

I thought that the Tuareg veil certainly did have its advantages, as did the fact that all the Tuareg dress alike in blue and white.

He said, 'There's another batch of sightings from hopefuls who'd like to win ten camels each. Twenty-two. Most of them duplicating the first lot.'

'Any possibles?'

He shrugged. 'Just that one on the Tassili n' Ajjer. Let's go talk to Paul. Where is he?'

'Down by the guelta. He spends a lot of time just looking at the water.'

So we went looking for Paul and found him, as I thought we would, sitting on the little sandy beach by the pool. Byrne sat on a rock and said, 'Paul, I want to talk to you.'

'What about?'

'I reckon you know more about your father's last flight than anyone in the world. I'd like your opinion on something.' He clicked his fingers at me. 'The map.'

The sun was dipping behind the hills but there was still enough light to see by. Byrne spread the map on the sand and traced a line with his finger. 'Algiers to Kano – that's the great circle course your father intended to fly. Right?'

Paul examined the line Byrne had drawn. 'Yes, that's about it.'

'It's not about anything,' said Byrne. That's the line.' He took the stub of pencil from the wallet which hung from his neck. 'Now we have one possibility – and it's here.' He marked the map with a cross.

Paul turned the map around. 'No,' he said firmly.

I 'Why not?'

'My father was a good pilot He'd never have gone so far off course.'

Byrne said, 'Remember I was a flier, too, so I know what I'm talking about. What time of day did he take off from Algiers?'

Paul said, 'He landed in Algiers just after midday. He didn't refuel immediately because his mechanic wanted to check the plane. That woman in Algiers said…'

'You mean Hesther Raulier?'

'Yes.'

'Then call her by her name,' said Byrne harshly. 'She is not "that woman in Algiers". Go on.'

Paul flinched. 'Hesther Raulier said there was an argument about that. My father wanted to refuel immediately and take off, but the mechanic wouldn't have it He said he wanted to have the plane just right.'

I said, 'Paul, in this race was time on the ground deducted from the elapsed time, or was it a case of whoever got to Cape Town first had won?'

'Whoever got to Cape Town first won outright.' I said to Byrne, 'Then every minute Peter Billson spent on the ground was a minute lost. It's not surprising he argued for a quick take-off.'

Byrne nodded. 'Who won the argument?'

'Must have been the mechanic,' said Paul. 'The wo – Hesther Raulier said she took my father to an hotel where he got some sleep.'

'Then when did he take off?'

'At five that afternoon.'

'That time of year it would be dark at six,' said Byrne. 'He was making a night flight. He wouldn't be able to tell from the ground whether he-was on course or not. He couldn't see the ground.'

'Hesther Raulier said it worried my father,' said Paul. 'Not the night flying, but he'd be landing at Kano in the dark. He didn't know if the airstrip would be illuminated.'

'Yeah,' said Byrne. That Northrop cruised at 215 mph, but he'd be pushing it a bit. Say eight hours to Kano landing at one in the morning. But he didn't get that far.'

It was now too dark to see the map clearly. I said, 'So what's the next move?'

'That's up to Paul,' said Byrne. 'I still think the plane was off course, and now I know it was a night flight that makes it certain to my mind.' He tapped the map. 'This could be Peter Billson's plane.'

I said, 'You'd be willing to take us there?'

'If that's what Paul wants.'

I looked towards Paul. I couldn't see his face but his movements showed indecision. At last he said hesitantly, 'Yes. All right.' Again no mention of thanks.

Byrne clapped his hands together lightly. 'We leave at dawn.'