ame from Biskra, and said: "Arrived here. Not spotted. He
went house of French commandant with no attempt at concealment. Am
waiting. Will wire again soon as have news. Perhaps better not start
till you hear."

An hour and a half later a second blue envelope was put into Nevill's
hand.

"He and an officer leave for Touggourt in private carriage three horses
relays ordered. Have interviewed livery stable. They start at five will
travel all night. I follow."

"Probably some officer was going on military business, and Maieddine's
asked for a lift," Nevill said to Lady MacGregor. "Well, it's too late
for us to get away now; but we'll be off as early as you like to-morrow
morning."

"If I weren't going, would you start to-day?" his aunt inquired.

"Yes, I suppose so. But----"

"Then please give orders for the car. I'm ready to leave at five
minutes' notice, and I can go on as long as you can. I'm looking forward
to the trip."

"But I've often offered to take you to Biskra."

"That's different. Now I've got an incentive."

XLII

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
Maieddine 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