CHAPTER XXIV.

BOB TRIES TO FLEE.

In an instant Jerry tried to turn the auto around. He found the passage too narrow. There was nothing to do but to back up the incline. This was a slow process in the darkness.

"Fire at them!" cried Ned.

"No. You might hit Bob!" said the professor. "We must chase after the brigands. This is what they have been following us for. I wonder what they want of Bob?"

No one could guess. By this time Jerry had run the machine up the inclined plane and into the temple. Then he sent it out into the street. It was as dark as a pocket and not a trace of the kidnappers could be seen, nor could they be heard. The capture of Bob came as a terrible blow.

"Let's take to the tunnel where we came in!" cried Ned. "Perhaps they are hiding there."

"If they are, they are well armed, and their force is three times what ours is now," said the professor. "If we are to help Bob we will have to do it by strategy rather than by force. Come, we had better go back to the temple. We can make our plans from there."

"Poor Chunky!" groaned Jerry. "I wonder what they are doing to him now?"

"I guess it was his money-belt they wanted more than they did him," put in Ned. "You know he carried what was left of the five hundred dollars."

"That's so!" exclaimed Jerry, with a rueful face.

"Never mind the money; I have plenty," put in the naturalist. "And don't worry; we'll find Bob yet."

Nothing could be done that night, so the professor and the two boys tried to get what sleep their troubled minds would allow. In the morning they made a hurried breakfast and then held a consultation. It was decided to explore the tunnel by which they had entered the city, and see if it still held the brigands and Noddy's crowd.

Arming themselves, the professor, Ned and Jerry advanced carefully through the big wooden gate. They proceeded cautiously, but no one opposed them. The tunnel was deserted. They came to the hole where they had tumbled down. The inclined plane of planks was there, in the same position as when the cave-in, produced by Murado, had occurred.

"They have probably gone back up here and are running across country," remarked Ned. "Hello!" he exclaimed. "What's that?"

He picked up a small object that lay at the foot of the incline, in the glare of the sunlight that streamed in from above.

"That's Bob's knife," said Jerry. "He had it yesterday. That shows he must have been here since. There is no doubt but that they have carried him away from here."

The professor agreed that this was probably the case. There was nothing left to do, so they returned to the temple.

"I hardly know what to do," said the naturalist. "We might take the automobile and ride off, not knowing where, in a vain endeavor to find Bob. Or we can stay here on the chance that he may escape and come back. If we went away he would not know where to find us.

"Then, too, I am hopeful we may hear something from Noddy Nixon or some of those Mexicans he had with him. Those fellows are regular brigands, and may have captured Bob, thinking we will pay a ransom for his return. On the whole, I think we had better stay here for a few days."

This seemed the best thing to do. With heavy hearts, Jerry and Ned wandered about the old temple, wishing their chum was back with them. The professor began to gather more specimens and made several trips to the old buildings where he got many curios of value.

Meanwhile, poor Bob was having his own troubles. At the first rough attack of the kidnappers, when he was hauled over the back of the auto, he did not know what had happened. He supposed it was some accident, such as the tunnel caving in or the water suddenly rising.

But when he found himself held by two men, and the bag thrown over his head, he realized that he was a captive, though he did not know why any one would want him.

Holding him between them, Vasco and Dalsett ran back into the bath and up the incline, followed by Noddy and the Mexicans. Berry and Pender had been left in charge of the auto and horses, which were in the first tunnel.

Bob, who had not attempted to struggle after his first involuntary kicking when he was hauled out, decided that his captors were having too easy a time of it. He was by no means a baby, and though he was fat he had considerable muscle.

So he began to beat about with his fists, and to kick with his heavy shoes, in a manner that made it very uncomfortable for Vasco and Dalsett.

"Quit that, you young cub, or I'll hurt you!" exclaimed Vasco.

"Yes, an' I'll do the same!" growled Dalsett, and, recognizing the voice, Bob knew for the first time into whose hands he had fallen.

He did not heed the command to stop struggling, and it was all the two men could do to hold him. Suddenly they laid him down.

"Look here!" exclaimed Dalsett, sitting on Bob to keep him still, "if you want us to tie you up like a steer we're willin' to do it. An' we'll gag you into the bargain. If you quit wigglin' you'll be treated decent."

"Then you take this bag off my head!" demanded Bob, with some spirit.

"I will if you promise to walk an' not make us carry you," promised Dalsett.

"I'll walk until I get a good chance to get away," replied Bob, determined to give no parole.

"Mighty little chance you have of gittin' away," remarked Dalsett, as he removed the sack.

It was as dark as a pocket, and Bob wondered where he was. Soon one of the men came with a lantern, and by the gleam the captive could see he was in the tunnel.

"Come on!" ordered Vasco.

Walking in the midst of his captors, Bob came to the foot of the incline. There he found Noddy, Pender and Bill Berry in the auto. The Mexicans had their horses in readiness for a flight.

"They're going to take me away," thought Bob. "I wonder how I can give the boys and the professor a sign so they will know that?"

His fingers came in contact with his knife and that gave him an idea. He dropped the implement on the ground, where it was found by his friends later.

"Is everything ready?" asked Vasco.

"I guess so," replied Noddy. "Shall I run the machine up the incline?"

"Go ahead," said Dalsett. "We'll walk with our young friend here. I reckon the car will have trouble gittin' up the hill if too many gits in it."

"Come on, you fellows!" ordered Vasco of his Mexicans. "We have the captive now, and you'll soon be dividing the ransom money." He spoke in Spanish, which Bob could not understand. The boy was at a loss why so many should be interested in him, but laid it all to a plot of Noddy's to get square.

It was quite a pull for the auto, up the steep incline, but Noddy, by using the low gear, managed it. The horses and their riders had less trouble, and soon the whole party stood in the road near the tunnel that led to the underground city.

Bob was placed on a small pony, and his hands were tied behind his back. Then, with a Mexican riding before and after him, and one on each side, the cavalcade started off.

For several hours the journey was kept up. No one said much, and poor Bob puzzled his brains trying to think what it all meant. One thing he determined on: that he would try to escape at the first opportunity.

It came sooner than he expected. He had been working at the bonds on his hands and found, to his joy, that the rope was coming loose. In their hurry, Vasco and Dalsett had not tied it very securely. In a little while Bob had freed his wrists, but he kept his hands behind his back, to let his captors think he was still bound.

He waited until he came to a level stretch of land. Then, at a time when the Mexican in the rear had ridden off to one side to borrow a cigarette of a comrade, Bob slipped from the pony's back.

He struck the ground rather hard, but here his fat served him in good stead, for he was not hurt much. Then he rolled quickly out of the way of the horses' feet.

Jumping up, he ran at top speed off to the left. Instantly the cavalcade was in confusion. Vasco and Dalsett came riding back to see what the trouble was. They saw Bob bounding away.

"After him!" shouted Vasco, drawing his revolver and firing in the air to scare Bob. "After him! He's worth ten thousand dollars!"

The Mexicans spurred their horses after the fugitive, while Noddy, turning the auto around, lighted the search-lamp and sent the light through the blackness to pick out Bob so the others could find him in the darkness.

On and on ran the boy, and after him thundered the horses of his pursuers, coming nearer and nearer.