For a moment Ned and Mr. Damon gazed at the farmer in his rattletrap of an auto, and then they looked at the fluttering piece of paper in his hand. Thence their gaze traveled to the ragged and barefoot lad sitting beside the farmer.

"I found it!" announced the boy.

"Found what?" asked Ned.

"That there note!"

Without asking any more questions, reserving them until they knew more about the matter, Mr. Damon and Ned each reached out a hand for the paper the farmer held. The latter handed it to Ned, being nearest him, and at a sight of the handwriting the young bank clerk exclaimed:

"It's from Tom, all right!"

"What happened to him?" cried Mr. Damon. "Where is he? Is he a prisoner?"

"So it seems," answered Ned. "Wait, I'll read It to you," and he read:

"'Whoever picks this up please send word at once to Mr. Swift or to Ned Newton in Shopton, or to Mr. Damon of Waterfield. I am a prisoner, locked in the old factory. Tom Swift'"

"Bless my quinine pills!" cried Mr Damon. "What in the world does it mean? What factory?"

"That's just what we've got to find out," decided Ned. "Where did you get this?" he asked the farmer's boy.

"Way off over there," and he pointed across miles of fields. "I was lookin' for a lost cow, and I went past an old factory. There wasn't nobody in the place, as far as I knowed, but all at once I heard some one yell, and then I seen something white, like a bird, sail out of a high window. I was scared for a minute, thinkin' it might be tramps after me."

"And what did you do, Sonny?" asked Mr. Damon, as the boy paused.

"Well, after a while I went to where the white thing lay, and I picked it up. I seen it was a piece of paper, with writin' on it, and it was wrapped around part of a brick."

"And did you go near the factory to find out who called or who threw the paper out?" Ned queried.

"I didn't," the boy answered. "I was scared. I went home, and didn't even start to find the lost cow.

"No more he did," chimed in the farmer. "He come runnin' in like a whitehead, and as soon as I saw the paper and heard what Bub had to say, I thought maybe I'd better do somethin'."

"Did you go to the factory?" asked Ned eagerly.

"No. I thought the best thing to do would be to find this Mr. Swift, or the other folks mentioned in this letter. I knowed, in a general way, where Shopton was, but I'd never been there, doing my tradin' in the other direction, and so I had to stop and ask the road. If you can tell me--"

"We're two of the persons spoken of in that note," said Mr. Damon, as he mentioned his name and introduced Ned. "We have been looking for our friend Tom Swift for two days now. We must find him at once, as there is no telling what he may be suffering."

"Where is this old factory you speak of," continued Mr. Damon, "and how can we get there? It's too bad one of you didn't go back, after finding the note, to tell Tom he was soon to be rescued."

"Waal, maybe it is," said the farmer, a bit put out by the criticism. "But I figgered it would be better to look up this young man's friends and let them do the rescuin', and not lose no time, 'specially as it's about as far from my place to the factory as it is to Shopton."

"Well, I suppose that's so," agreed Ned. "But what is this factory?"

"It's an old one where they started to make beet sugar, but it didn't pan out," the farmer said. "The place is in ruins, and I did hear, not long ago, that somebody run a threshin' machine through it, an' busted it up worse than before."

"Great horned toads!" cried Ned. "That must be the very factory Tom ran his tank through. And to think he should be a prisoner there!"

"Held by whom, do you suppose?" asked Mr. Damon.

"By that Blakeson gang, I imagine," Ned answered. "There's no time to lose. We must go to his rescue!"

"Of course!" agreed Mr. Damon. "We're much obliged to you for bringing this note," he went on to the farmer. "And here is something to repay you for your trouble," and he took out his wallet

"Shucks! I didn't do this for pay!" objected the farmer. "It's a pity I wouldn't help anybody what's in trouble! If I'd a-knowed what it meant, me and Bub here would have gone to the factory ourselves, maybe, and done the work quicker. But I didn't know--what with war times and such-like--but that it would be better to deliver the note."

"It turns out as well, perhaps," agreed Ned. "We'll look after Tom now."

"And I'll come along and help," said the farmer. "If there's a gang of tramps in that factory, you may need some reinforcements. I've got a couple of new axe handles in my machine, and they'll come in mighty handy as clubs."

"That's so," said Mr. Damon. "But I fancy Tom is simply locked in the deserted factory office, with no one on guard. We can get him out once we get there, and we'll be glad to have you come with us. So if you won't take any reward, maybe your boy will, as he found the note," and Mr. Damon pressed some bills into the hands of the boy, who, it is needless to say, was glad to get them.

It was a run of several miles hack to the deserted factory, and though they passed houses on the way, it was decided that no addition to their force was necessary, though they did stop at a blacksmith shop, where they borrowed a heavy sledge to batter down a door if such action should be needed.

The farmer's rattletrap of a car, in spite of its appearance, was not far behind Ned's runabout, and in a comparatively short time all were within sight of the ruined place--a ruin made more complete by the passage through it of Tom Swift's war tank.

"And to think of his being there all this while!" exclaimed Mr. Damon, as he and Ned leaped from their machine.

"If he only is there!" murmured the young bank clerk.

"What do you mean? Didn't the note he threw out say he was there?"

"Yes, but something may have happened in the meanwhile. Those plotters, if they'd do a thing like this, are capable of anything. They may have kidnapped Tom again."

"Anyway, we'll soon find out," murmured Ned, as they advanced toward the ruin, Mr. Damon and the farmer each armed with an axe helve, while Ned carried the blacksmith's sledge.

They went into the end of the factory that was less ruined than the central part, where the tank had crashed through, and made their way into what had been the office--the place where they had found the burned scraps of paper.

"Hark!" exclaimed Ned, as they climbed up the broken steps. "I heard a noise."

"It's him yellin'--like he did afore he threw out the note," said the boy. Then, as they listened, they heard a distant voice calling:

"Hello! Hello, there! If that is any friend of mine, let me out, or send word to Mr. Damon or Ned Newton! Hello!"

"Hello yourself, Tom Swift!" yelled Ned, too delighted to wait for any other confirmation that it was his friend who was shouting. "We've come to rescue you, Tom!"

There was a moment of silence, and then a voice asked:

"Who is there?"

"Ned Newton, Mr. Damon, and some other friends of yours!" answered the young bank clerk, for surely the farmer and his son could be called Tom's friends.

An indistinguishable answer came back, and then Ned cried:

"Where are you, Tom? Tell us, so we can get you out!"

They all listened, and faintly heard:

"I'm in some sort of an old vault, partly underground. It's below what used to be the office. There's a flight of steps, but be careful, as they're rotten."

Eagerly they looked around Mr. Damon saw a door in one corner of the office, and tried to open it. It was locked, but a few blows from the sledge smashed it, and then some steps were revealed.

Down these, using due caution, went Ned and the others, and at the bottom they came upon another door. This was of sheet iron and was fastened on the outside by a big padlock.

"Stand back!" cried Ned, as he swung the sledge, and with a few blows broke the lock to pieces.

Then they pulled open the door, and into the light staggered Tom Swift, a most woe-begone figure, and showing the effects of his imprisonment. But he was safe and unharmed, though much disheveled from his attempts to escape.

"Thank Heaven, you've come!" he murmured, as he clasped Ned's hand. "Is the tank all right?"

"All right!" cried Ned. "And now tell us about yourself. How in the world did you get here?"

"It's quite a yarn," answered Tom. "I've got to pull myself together before I answer," and he sank wearily down on a step, looking very haggard and worn.