BOB and Joe gasped in astonishment.

“The train wrecked!” muttered Bob and then started. “What caused it?”

“I imagine you’re thinking the same as I,” the archÆologist said quietly. “That those thieves were responsible for it to prevent us from getting to Wargla at once.”

Joe’s face glowed with anger.

“The dirty beggars!” he cried. “Was anyone hurt?”

“No. It happened that no one was. But the locomotive was derailed and lodged in a ravine, and the work of getting it back on the track and repairing it won’t start any too soon in this country. It may be two or three days before order will be restored. It looks like those robbers have won out after all.”

They walked on into the room, where they were met by the boys’ fathers and Fekmah.

“Is there anything wrong?” asked Mr. Holton, as he noticed the sober faces of his friends.

The situation was explained, and the men frowned. Fekmah especially was agitated.

“May the black monsters of Tidihet feast on them!” he exclaimed, running his fingers through his white hair. “Allah will punish them—they will not go free!”

“But that won’t help us any,” said Mr. Lewis dryly. “We’ve got to figure out some way to stop them, if it’s at all possible. The question is, what will it be?”

“There’s no way of telegraphing,” said Dr. Kirshner, gazing thoughtfully at the floor. “If we had any idea where they went—that is, what route they took—we might overtake them on fast dromedaries. But the chances even then would be slight.”

“We might——” began Joe but was interrupted by a knock at the door.

For a moment the adventurers looked at one another in surprise. Then Mr. Holton moved over and cautiously opened the door.

The figure that stood in waiting was a tall, powerful Arab, with dark, piercing eyes that were none too pleasant to look at. He towered several inches above Mr. Holton, who was himself nearly six feet. Around the man’s shoulders and reaching nearly to the floor was a white gown, and on his head was the conventional hlafa.

For several moments he stood looking at the occupants of the room, as though forming a rapid opinion of the situation. Then he again turned to Mr. Holton and muttered something in the native tongue.

That Bob’s father understood was evidenced by the look of surprise that came on his face. A moment later he turned to his friends.

“He says Fekmah is wanted by a friend,” Mr. Holton said. “Won’t say any more. I don’t know what to make of it.”

“A friend?” Fekmah gasped. “Why, I know no person here. What could it mean?”

Again the stranger said something in Arabic and motioned for his objective to come out.

For a moment Fekmah was thoughtful. Then he decided to investigate.

“I will be back in short minutes,” he said and walked toward the door.

“Wait a minute,” called Dr. Kirshner. “I’m going with you.”

“And I, too,” cried Bob, getting up from his chair.

Joe also put in a request, but the archÆologist shook his head.

“Two more are enough,” he said quietly, as he and Bob followed the Arab down the hall.

“Be careful,” warned Mr. Lewis, as they reached the stairs. “There’s no telling what that fellow may want.”

They reached the street and were directed around the corner and up a narrow byway, the stranger remaining several yards in the van.

“Keep a ready hand on your automatic,” whispered Dr. Kirshner to Bob. “Something may happen in a short time now.”

“Do you believe Fekmah is really wanted by friends?” the youth asked, glancing about as if he expected any minute to be confronted by a band of desperate characters.

“Beyond me,” was the reply. “But I believe it would be safer to say no than yes. But there is a possibility that he met someone and has forgotten about it.”

“What could they want of him? It all seems funny to me.”

On they went, now upward by a gently sloping street that was so crooked it seemed to have no outlet.

Suddenly the street stopped at a narrow, winding stairway that led almost straight up. All about were crowded houses of clay, dirty and weather-beaten and suggesting that only the very poorest of Arabs lived there.

Having made sure that the others were following him, the stranger led the way up the stairs. At the head was a small door, and this was opened for them to go inside.

But they hesitated.

“Ask him what he wants,” directed Bob. “There could be anything in there.”

Dr. Kirshner turned to the Arab and in a stern voice put the question before him.

The latter surveyed the American closely, then said in the native tongue:

“I wish nothing of you. It is Fekmah who is wanted. But if you and your friend must intrude, you may come in.”

The man’s attitude did not win the friendship of the explorers, but chiefly because they were at a loss to know what to do next they followed him inside.

A moment later the door was closed and they found themselves in a sort of twilight.

As soon as their eyes became accustomed to the dim light, they made out four figures sitting in the corner of the room. The bare floor alone served the place of chairs, and the men seemed comfortable. Bob at once formed the conclusion that these Arabs were of the same type as the stranger who escorted them here, and felt a bit uneasy. He would have felt much better with a hand on his gun, but this would have aroused the suspicions of the natives. Nevertheless he kept on guard for any treachery. If it came to a fight, he knew that it would be two to five, for Fekmah was, in his age, not capable of taking part.

None of the Arabs was able to speak English, evidently, but Dr. Kirshner knew the native language from his previous visits to North Africa. And he promised to translate occasionally to Bob.

But a moment later it was plain that there was little translating to be done, for one of the Arabs said something to Fekmah and motioned for him to come into the next room. The Americans were to remain where they were.

“I don’t like this,” muttered Dr. Kirshner, as he and Bob were told to be seated on the floor. “Anything may happen to him in there.”

“Suppose we go with him,” suggested Bob.

The archÆologist nodded. He arose from his chair and started to follow, but one of the Arabs gently pushed him back.

“It is Fekmah who is wanted,” the fellow said in a queer bass voice. “You will wait here. It will only be a moment.”

Dr. Kirshner had half a notion to push through and follow his Arab friend, but he changed his mind and sat down with Bob on the floor.

“What’s the big idea of all this?” the youth asked in a puzzled voice. “They trying to double-cross us or something?”

The archÆologist did not answer, for he felt all too sure that something serious was wrong. But what was there to do?

There was no conversation between the archÆologist and the natives, for each seemed busy with his thoughts. Bob was extremely grave, and he wondered what was taking place in the adjoining room. Perhaps the Arabs wished to sell Fekmah something and did not wish to be thwarted by the whites. Or perhaps they wanted to engage themselves as guides on the coming expedition and knew they would have a better chance with Fekmah than with the Americans. But whatever it was, Bob felt uneasy. If their friend did not return before long he would go after him, the youth thought.

“We’ll wait a few more minutes,” said Dr. Kirshner. “Then——”

“Listen!” commanded Bob. “What was that?”

“I didn’t hear anything. What——”

“There it is again. Sounds like a muffled cry for help. It’s—it’s Fekmah!”