Just as he came in sight of the great chott between Biskra and Touggourt, Stephen heard a sound which struck him strangely in the silence of the desert. It was the distant teuf-teuf of a powerful motor car, labouring heavily through deep sand.

Stephen was travelling in a carriage, which he had hired in Biskra, and was keeping as close as he dared to the vehicle in front, shared by MaÏeddine and a French officer. But he never let himself come within sight or sound of it. Now, as he began to hear the far-off panting of a motor, he saw nothing ahead but the vast saltpetre lake, which, viewed from the hill his three horses had just climbed, shimmered blue and silver, like a magic sea, reaching to the end of the world. There were white lines like long ruffles of foam on the edges of azure waves, struck still by enchantment while breaking on an unseen shore; and far off, along a mystic horizon, little islands floated on the gleaming flood. Stephen could hardly believe that there was no water, and that his horses could travel the blue depths without wetting their feet.

It was just as he was thinking thus, and wondering if Victoria had passed this way, when the strange sound came to his ears, out of the distance. "Stop," he said in French to his Arab driver. "I think friends of mine will be in that car." He was right. A few minutes later Nevill and Lady MacGregor waved to him, as he stood on the top of a low sand-dune.

Lady MacGregor was more fairylike than ever in a little motoring bonnet made for a young girl, but singularly becoming to her. They had had a glorious journey, she said. She supposed some people would consider that she had endured hardships, but they were not worth speaking of. She had been rather bumped about on the ghastly desert tracks since Biskra, but though she was not quite sure if all her bones were whole, she did not feel in the least tired; and even if she did, the memory of the Gorge of El Kantara would alone be enough to make up for it.

"Anything new?" asked Nevill.

"Nothing," Stephen answered, "except that the driver of the carriage ahead let drop at the last bordj that he'd been hired by the French officer, who was taking MaÏeddine with him."

"Just what we thought," Lady MacGregor broke in.

"And the carriage will bring the Frenchman back, later. MaÏeddine's going on. But I haven't found out where."

"H'm! I was in hopes we were close to our journey's end at Touggourt," said Nevill. "The car can't get farther, I'm afraid. The big dunes begin there."

"Whatever MaÏeddine does, we can follow his example. I mean, I can," Stephen amended.

"So can Nevill. I'm no spoil-sport," snapped the old lady, in her childlike voice. "I know what I can do and what I can't. I draw the line at camels! Angus and Hamish will take care of me, and I'll wait for you at Touggourt. I can amuse myself in the market-place, and looking at the Ouled NaÏls, till you find Miss Ray, or——"

"There won't be an 'or,' Lady MacGregor. We must find her. And we must bring her to you," said Stephen.

He had slept in the carriage the night before, a little on the Biskra side of Chegga, because MaÏeddine and the French officer had rested at Chegga. Nevill and Lady MacGregor had started from Biskra at five o'clock that morning, having arrived there the evening before. It was now ten, and they could make Touggourt that night. But they wished MaÏeddine to reach there first, so they stopped by the chott, and lunched from a smartly fitted picnic-basket Lady MacGregor had brought. Stephen paid his Arab coachman, told him he might go back, and transferred a small suitcase—his only luggage—from the carriage to the car. They gave MaÏeddine two hours' grace, and having started on, always slowed up whenever Nevill's field-glasses showed a slowly trotting vehicle on the far horizon. The road, which was hardly a road, far exceeded in roughness the desert track Stephen had wondered at on the way from Msila to Bou-Saada; but Lady MacGregor had the courage, he told her, of a Joan of Arc.

They bumped steadily along, through the heat of the day, protected from the blazing sun by the raised hood, but they were thankful when, after the dinner-halt, darkness began to fall. Talking over ways and means, they decided not to drive into Touggourt, where an automobile would be a conspicuous object since few motors risked springs and tyres by coming so far into the desert. The chauffeur should be sent into the town while the passengers sat in the car a mile away.

Eventually Paul was instructed to demand oil for his small lamps, by way of an excuse for having tramped into town. He was to find out what had become of the two men who must have arrived about an hour before, in a carriage.

While the chauffeur was gone, Lady MacGregor played Patience and insisted on teaching Stephen and Nevill two new games. She said that it would be good discipline for their souls; and so perhaps it was. But Stephen never ceased calculating how long Paul ought to be away. Twenty minutes to walk a mile—or thirty minutes in desert sand; forty minutes to make inquiries; surely it needn't take longer! And thirty minutes back. But an hour and a half dragged on, before there was any sign of the absentee; then at last, Stephen's eye, roving wistfully from the cards, saw a moving spark at about the right height above the ground to be a cigarette.

A few yards away from the car, the spark vanished decorously, and Paul was recognizable, in the light of the inside electric lamp, the only illumination they allowed themselves, lest the stranded car prove attractive to neighbouring nomads.

The French officer was at the hotel for the night; the Arab was dining with him, but instead of resting, would go on with his horse and a Negro servant who, it seemed, had been waiting for several days, since their master had passed through Touggourt on the way to Algiers.

"Then he didn't come from El Aghouat," said Nevill. "Where is he going? Did you find out that?"

"Not for certain. But an Arab servant who talks French, says he believes they're bound for a place called Oued Tolga," Paul replied, delighted with the confidence reposed in him, and with the whole adventure.

"That means three days in the dunes for us!" said Nevill. "Aunt Charlotte, you can practice Patience, in Touggourt."

"I shall invent a new game, and call it Hope," returned Lady MacGregor. "Or if it's a good one, I'll name it Victoria Ray, which is better than Miss Millikens. It will just be done in time to teach that poor child when you bring her back to me."

"Hope wouldn't be a bad name for the game we've all been playing, and have got to go on playing," mumbled Nevill. "We'll give MaÏeddine just time to turn his back on Touggourt, before we show our noses there. Then you and I, Legs, will engage horses and a guide."

"You deserve your name, Wings," said Stephen. And he wondered how Josette Soubise could hold out against Caird. He wondered also what she thought of this quest; for her sister Jeanne was in the secret. No doubt she had written Josette more fully than Nevill had, even if he had dared to write at all. And if, as long ago as the visit to Tlemcen, she had been slightly depressed by her friend's interest in another girl, she must by this time see the affair in a more serious light. Stephen was cruel enough to hope that she was unhappy. He had heard women say that no cure for a woman's obstinacy was as sure as jealousy.

When they arrived at the hotel, and ordered all in the same breath, a room for a lady, two horses and a guide, only the first demand could be granted. It would be impossible, said the landlady and her son, to produce horses on the instant. There were some to be had, it was true, but they had come in after a hard day's work, and must have several hours' rest. The gentlemen might get off at dawn, if they wished, but not before.

"After all, it doesn't much matter," Nevill said to Stephen. "Even an Arab must have some sleep. We'll have ours now, and catch up with MaÏeddine while he's taking his. Don't worry. Suppose the worst—that he isn't really going to Oued Tolga. We shall get on his track, with an Arab guide to pilot us. There are several stopping places where we can inquire. He'll be seen passing them, even if he goes by."

"But you say Arabs never betray each other to white men."

"This won't be a question of betrayal. Watch and see how ingenuous, as well as ingenious, I'll be in all my inquiries."

"I never heard of Oued Tolga," Stephen said, half to himself.

"Don't confess that to an Arab. It would be like telling a Frenchman you'd never heard of Bordeaux. It's a desert city, bigger than Touggourt, I believe, and—by Jove, yes, there's a tremendously important ZaouÏa of the same name. Great marabout hangs out there—kind of Mussulman pope of the desert. I hope to goodness——"

"What?" Stephen asked, as Nevill broke off suddenly.

"Oh, nothing to fash yourself about, as the twins would say. Only—it would be awkward if she's there. Harder to get her out. However—time to cross the stile when we come to it."

But Stephen crossed a great many stiles with his mind before that darkest hour before the dawn, when he was called to get ready for the last stage of the journey.

Lady MacGregor was up to see them off, and never had her cap been more elaborate, or her hair been dressed more daintily.

"You'll wire me from the end of the world, won't you?" she asked briskly. "Paul and I (and Hamish and Angus if necessary) will be ready to rush you all three back to civilization the instant you arrive with Miss Ray. Give her my love. Tell her I've brought clothes for her. They mayn't be what she'd choose, but I dare say she won't be sorry to see them. And by the way, if there are telegrams—you know I told the servants to send them on from home—shall I wire them on to Oued Tolga?"

"No. We're tramps, with no address," laughed Nevill. "Anything that comes can wait till we get back."

Stephen could not have told why, for he was not thinking of Margot, but suddenly he was convinced that a telegram from her was on the way, fixing the exact date when she might be expected in England.