"Hello!" cried Tom. "What's up, Koku?"

"Him up!" replied the giant with a laugh, as he looked at his squirming prisoner, whose feet he had lifted from the ground.

"No, I mean what was he doing?" went on Tom, with a smile at the literal way in which the giant had answered his question.

"I wasn't doing anything!" broke in the man. "I'd like to know if I haven't a right to walk through these woods, without being grabbed up by a man as big as a mountain? There'll be something up that you won't like, if you don't let me go, too!" and he struggled fiercely, but he was no match for giant Koku.

"What was he doing?" asked Tom of his big servant, ignoring the man. Tom looked closely at him, however, but could not remember to have seen him before.

"I walking along in woods, listen to birds sing," said Koku simply, taking a firmer hold on his victim. "I see this fellow come along, and crawl through grass like so a snake wiggle. I to myself think that funny, and I watch. This man he wiggle more. He wiggle more still, and then he watch. I watch too. I see him have knife in hand, but I am no afraid. I begin to go like snake also, but I bigger snake than he."

"I guess so," laughed Tom, as he watched the man trying in vain to get out of Koku's grip.

"Then I see man look up at balloon bag, so as if he like to cut it with knife. I say to myself, 'Koku, it is time for you to go into business for yourself.' You stand under me?"

"I understand!" exclaimed Tom. "You thought it was time for you to get busy."

"Sure," replied Koku. "Well, I get business, I give one jump, and I am so unlucky as to jump with one foot on him, but I did not mean it. I go as gentle as I can."

"Gentle? You nearly knocked the wind out of me!" snarled the prisoner. "Gentle! Huh!"

"I guess he was the unlucky one, instead of you," put in Tom. "Well, what happened next?"

"I grab him, and--he is still here," said Koku simply. "He throw knife away though."

"I see," spoke Tom. "Now will you give an account of yourself, or shall I hand you over to the police?" he asked sternly of the man. "What were you sneaking up on us in that fashion for?"

"Well, I guess this isn't your property!" blustered the man. "I have as good a right here as you have, and you can't have me arrested for that."

"Perhaps not," admitted Tom. "You may have a right on this land, but if you are honest, and had no bad intentions, why were you sneaking up, trying to keep out of sight? And why did you have a big knife?"

"That's my business, young man."

"All right, then I'll make it my business, too," went on the young inventor. "Hold him, Koku, until I can find Mr. Damon, or Ned, and I'll see what's best to be done. I wish Mr. Whitford was here."

"Aren't you going to let me go?" demanded the man.

"I certainly am not!" declared Tom firmly. "I'm going to find out more about you. I haven't any objections to any one coming to look at my airship, out of curiosity, but when they come up like a snake in the grass and with a big knife, then I get suspicious, and I want to know more about them."

"Well, you won't know anything more about me!" snarled the fellow. "And it will be the worse for you, if you don't let me go. You'd better!" he threatened.

"Don't pay any attention to him, Koku," said Tom. "Maybe you'd better tie him up. You'll find some rope in the motor room."

"Don't you dare tie me up!" blustered the prisoner.

"Go ahead and tie him," went on Tom. "You'll be free to guard the ship then. I'll go for Ned and Mr. Damon."

"Tie who up? What's the matter?" asked a voice, and a moment later the government agent came along the woodland path on his horse. "What's up, Tom? Have you captured a wild animal?"

"Not exactly a wild animal. Mr. Whitford. But a wild man. I'm glad you came along. Koku has a prisoner." And Tom proceeded to relate what had happened.

"Sneaking up on you with a knife; eh? I guess he meant business all right, and bad business, too," said Mr. Whitford. "Let me get a look at him, Tom," for Koku had taken his prisoner to the engine room, and there, amid a storm of protests and after a futile struggle on the part of the fellow, had tied him securely.

Tom and the custom officer went in to look at the man, just as Ned and Mr. Damon came back from their stroll in the woods. It was rapidly getting dusk, and was almost time for the start of the usual flight, to see if any trace could be had of the smugglers.

"There he is," said Tom, waving his hand toward the bound man who sat in a chair in one corner of the motor room. The young inventor switched on the light, and a moment later Mr. Whitford exclaimed:

"Great Scott! It's Ike Shafton!"

"Do you know him?" asked Tom eagerly.

"Know him? I should say I did! Why he's the man who pretended to give one of my men information about smugglers that drew us off on the false scent. He pretended to be for the government, and, all the while, he was in with the smugglers! Know him? I should say I did!"

A queer change had come over the prisoner at the sight of Mr. Whitford. No longer was Shafton surly and blustering. Instead he seemed to slink down in his chair, bound as he was, as if trying to get out of sight.

"Why did you play double?" demanded the government agent, striding over to him.

"I--I--don't hit me!" whined Shafton.

"Hit you! I'm not going to hit you!" exclaimed Mr. Whitford, "but I'm going to search you, and then I'm going to wire for one of my men to take you in custody."

"I--I didn't do anything!"

"You didn't; eh? Well, we'll see what the courts think of giving wrong information to Uncle Sam with the intent to aid criminals. Let's see what he's got in his pockets."

The spy did not have much, but at a sight of one piece of paper Mr. Whitford uttered a cry of surprise.

"Ha! This is worth something!" he exclaimed. "It may be stale news, and it may be something for the future, but it's worth trying. I wonder I didn't think of that before."

"What is it?" asked Tom.

For answer the custom officer held out a scrap of paper on which was written one word.

ST. REGIS.

"What does it mean," asked Ned, who, with Mr. Damon, had entered the motor room, and stood curiously regarding the scene.

"Bless my napkin ring!" said the odd man. "That's the name of a hotel. Do you suppose the smugglers are stopping there?"

"Hardly," replied Mr. Whitford with a smile. "But St. Regis is the name of an Indian reservation in the upper part of New York state, right on the border, and in the corner where the St. Lawrence and the imaginary dividing line between New York and Canada join. I begin to see things now. The smugglers have been flying over the Indian Reservation, and that's why they have escaped us so far. We never thought of that spot. Tom, I believe we're on the right track at last! Shafton was probably given this to inform him where the next trick would be turned, so he could get us as far away as possible, or, maybe prevent us leaving at all."

An involuntary start on the part of the prisoner seemed to confirm this, but he kept silent.

"Of course," went on Mr. Whitford, "they may have already flown over the St. Regis reservation, and this may be an old tip, but it's worth following up."

"Why don't you ask him?" Tom wanted to know, as he nodded toward Shafton.

"He wouldn't tell the truth. I'll put him where he can't get away to warn his confederates, and then we'll go to the reservation. And to think that my man trusted him!"

Mr. Whitford was soon in communication with his headquarters by means of the wireless apparatus on Tom's airship, and a little later two custom officers arrived, with an extra horse on which they were to take their prisoner back.

"And now we'll try our luck once more," said Mr. Whitford as his men left with Shafton securely bound. "Can you make the reservation in good time, Tom? It's quite a distance," and he pointed it out on the map.

"Oh, I'll do it," promised the young inventor, as he sent his powerful craft aloft in the darkness. Then, with her nose pointed in the right direction, the Falcon beat her way forward through the night, flying silently, with the great searchlight ready for instant use.

In comparatively short time, though it was rather late at night, they reached the St. Lawrence, and then it was an easy matter to drop down into the midst of the reservation grounds. Though the redmen, whom the state thus quartered by themselves, had all retired, they swarmed out of their cabins as the powerful light flashed back and forth.

"We want to question some of the head men of the tribe," said Mr. Whitford. "I know some of them, for on several occasions I've had to come here to look into rumors that tobacco and liquor and other contraband goods dear to the Indian heart were smuggled into the reservation against the law. I never caught any of them at it though."

With guttural exclamations, and many grunts of surprise, the redmen gathered around the big airship. It was too much even for their usual reserve, and they jabbered among themselves.

"How Big Foot!" greeted the custom officer, to one Indian who had an extremely large left foot. "How!"

"How!" responded the Indian, with a grunt.

"Plenty much fine air-bird; eh?" and the agent waved his hand toward the Falcon.

"Yep. Plenty much big."

"Big Foot never see bird like this; eh?"

"Oh sure. Big Foot see before many times. Huh!"

"What! Has he seen this before?" asked Tom.

"No. Wait a minute," cautioned Mr. Whitford. "I'm on the track of something. Big Foot see air-bird like this?" he questioned.

"Sure. Fly over Indians' land many times. Not same as him," and he nodded toward Tom's ship, "but plenty much like. Make heap noise. Come down once--break wheel mebby. Indians help fix. Indians get firewater. You got firewater in your air-bird?"

"No firewater, but maybe we've got some tobacco, if you tell us what we want to know, Big Foot. And so you've seen air-birds flying around here before?"

"Sure, Heap times. We all see," and he waved his hand to indicate the redmen gathered around him.

There came grunts of confirmation.

"We're getting there!" exclaimed Mr. Whitford to Tom. "We're on the right track now. Which way air-birds come, Big Foot?"

"Over there," and he pointed toward Canada.

"Which way go?"

"Over there," and he pointed toward the east, in the direction of Shopton, as much as anywhere.

"That's what we want to know. Tom, we'll just hang around here for a while, until one of the smugglers' airships pass over head. I believe one is due to-night, and that's why Shafton had that paper. It was sent to him to tip him off. He was sneaking up, trying to put your airship out of commission when Koku caught him. These Indians have used their eyes to good advantage. I think we're on the trail at last."

"Baccy for Big Foot?" asked the redman.

"Yes, plenty of it. Tom, give them some of Koku's, will you? I'll settle with you later," for the giant had formed a liking for the weed, and Tom did not have the heart to stop him smoking a pipe once in a while. With his usual prodigality, the giant had brought along a big supply, and some of this was soon distributed among the Indians, who grunted their thanks.