Jack said, 'I'll tell you something, Max; someone else is looking for Billson. We've been crossing their tracks.'

The police?'

'I don't think so. Not their style.'

'The Special Branch, then?'

'Could be. They move in mysterious ways their wonders to perform.'

I stretched out an arm for the telephone. 'I'll ask.'

Because some of our clients, such as Franklin Engineering, were into defence work, contact with the Special Branch was inevitable for Stafford Security. It was an uneasy relationship and we were tolerated only because we could take off them some of their work load. If, for example, we saw signs of subversion we tipped them off and were rewarded by being left alone. A strictly confidential relationship, of course; the trades unions would have raised hell had they known.

The man I rang was politely amused. 'Billson is no concern of ours. We checked back on what you told us; we even interviewed that bloody journalist – now there's a slimy bit of work. As far as we're concerned, Billson is a semi-paranoiac who has gone off the rails a bit. He might interest a psychiatrist, but he doesn't interest us.'

'Thanks.' I put down the telephone and said to Jack, 'He says they aren't interested, but would he tell me the truth?' I frowned as I turned the pages of the report. 'Algiers! Why didn't Billson apply for an Algerian visa?'

'He didn't need to. British citizens don't need visas for Algeria.' Jack produced another thin file. 'About Sir Andrew McGovern. Relationship with Billson – apart from the fact that they're remotely linked through Franklin Engineering -nil. Relationship with Alix Aarvik – nil. It's a straight master-and-servant deal – they're not even "just good friends". The Kisko Nickel Corporation is undergoing an internal reorganization due to a merger which McGovern engineered. But Alix Aarvik didn't go to Canada; she's still operating as Mc-Govern's secretary.'

I shrugged. 'As I once said to Brinton, the best thing about advice is that you needn't take it.' I smiled sourly. 'It turned out that his advice was good, but that's no reason for Alix Aarvik to take mine.'

'Apart from that there's not much to get hold of in McGovern,' said Jack. 'He does seem to live in Brinton's pocket.'

'Not quite,' I said absently. 'Brinton has been having trouble with him. That's why we lost the Whensley account.' I was thinking of the Sahara; of how big and empty it was.

Jack sniffed. 'If they have quarrelled no one would notice it McGovern entertained Brinton at his home two days ago.'

I said, 'If Brinton pats Andrew McGovern on the back it's just to find a good spot to stick the knife. Thanks, Jack; you've done a good job. I'll take it from here.'

When he had gone I rang Whensley Holdings and asked for Miss Aarvik. When she came on the line I said, 'Max Stafford here. So you didn't go to Canada, after all.'

'Sir Andrew changed his mind.'

'Did he? Miss Aarvik, I have some information about your brother which I think you ought to know. Will you have dinner with me tonight?'

She hesitated, then said, 'Very well. Thank you for your continued interest in my brother, Mr Stafford.'

'I'll call for you at your flat at seven-thirty,' I said.

After that I went down to the club library, took down The Times Atlas, and studied a map of the Sahara for a long time. It didn't take me as long as that to find out that the idea burgeoning in my. mind was totally fantastic, utterly irresponsible and probably bloody impossible.

I picked up Alix Aarvik that evening and took her to a French restaurant, an unpretentious place with good food. It was only after we had chosen from the menu that I opened the subject over a couple of sherries. I told her where Paul Billson was.

'So he is trying to find the plane,' she said. 'But it's totally impossible. He's not the man to…' She stopped suddenly. 'How can he afford to do that?'

I sighed. Alix Aarvik was due to receive a shock. 'He's been holding out on you. Probably for a long time, judging by the cash he squirrelled away. He was getting?8000 a year from Franklin Engineering.'

It took a while for it to sink in, but as it did her face went pale and pink spots appeared in her cheeks. 'He could do that\' she whispered, lie could let me pay his bills and not put up a penny for Mother's support.'

She was becoming very angry. I liked that; it was time someone got mad at Paul Billson. I wasn't so cool about him myself. I said, 'I'm sorry to have administered the shock, but I thought you ought to know.'

She was silent for a while, looking down into her glass and aimlessly rotating the stem between her fingers. At last she said, 'I just don't understand him.'

'It seems he didn't abandon his boyhood dream. He saved up his money to fulfil it.'

'At my expense,' she snapped. She gave a shaky laugh. 'But you must be wrong, Mr Stafford. I know what Paul was doing at Franklin Engineering. They wouldn't pay him that much.'

'That's another mystery. It seems they did. Your brother had damn near?60,000 to his name when he pushed off -and he turned it all into hard cash. If he's taken it with him to Algiers he's put a hell of a crimp into the currency regulations. I think Paul is now a law-breaker.'

'But this is ridiculous.'

'I agree – but it's also true; Paul has gone to look for his father's plane. I can't think of any other reason why he should shoot off to Algiers with a Land-Rover. He's looking for a plane which crashed over forty years ago and that's a hell of a long time. I was looking at a map this afternoon. Do you know how big the Sahara is?' She shook her head and I said grimly, 'Three million square miles – just about the same size as the United States but a hell of a lot emptier. It'll be like searching the proverbial haystack for the needle, with the difference that the needle might not be there.'

'What do you mean by that?'

'Suppose Hendrik van Niekirk really did see Peter Billson in Durban after he was supposed to have crashed. You can lay ten to one that Billson wouldn't have left that plane lying around for anyone to find. If he was a faker after that insurance money my guess is that he'd ditch off-shore in the Mediterranean. He'd row himself ashore in a collapsible dinghy – they had those in 1936, I've checked – and get himself lost. So Paul might be looking for something in the desert that's not there.'

'I don't like that,' she said coldly. 'You're implying that my mother was party to a fraud.'

'I'm sorry,' I said. 'I don't like it much myself, but it's a possibility that has to be considered. I do it all the time in my business, Miss Aarvik.'

A waiter interrupted us by bringing the first course. Over the onion soup I said, 'Anyway, that's where your brother is – somewhere in Algeria if he isn't already in Niger or Chad or somewhere else as improbable.'

'He must be brought back,' she said. 'Mr Stafford, I don't have much money, but is it at all possible for your detective agency to look for him?'

'I don't run a detective agency,' I said. 1 run a security organization. Lots of people get the two confused. Frankly, I don't see why you want him back. You've just heard of how he's been deceiving you for years. I think you're better off without him.'

'He's my brother,' she said simply. 'He's the only family I have in the world.'

She looked so woebegone that I took pity on her. I suppose it was then the decision was made. Of course I hedged it about with 'ifs' and 'maybes' as a sop to my conscience should I renege, but the decision was made.

I said carefully, 'There's a possibility – just a possibility, mind you – that I may be going to North Africa in the near future. If I do, I'll ask around to see if I can find him.'