In a few minutes the door opened and the man stepped out, stopping to fasten it securely behind him. Then, with a quick glance about the little clearing, he made for the path leading to the main road and in a short time the sound of his going died away.

The boys waited a few minutes, thinking that possibly he might return for something forgotten, but no further sound came from the path. At length they ventured to approach the deserted cabin.

The door had been fastened with a heavy padlock, but this was not sufficient to deter the radio boys. Searching through their pockets for some implement with which they could undo the lock, Jimmy discovered a stout fish-hook, and after they had ground off the barbs against a flat stone this made an ideal tool. With it Bob probed about in the interior of the padlock, and at length, with a sharp click, it sprung open.

Ordinarily he would not have done this, but he had every reason to believe that he was dealing with a criminal and that he was justified in the interest of law and order in taking steps that would prevent any further depredations against society.

"More ways than one of killing a cat," remarked Bob, as he pushed open the heavy door and entered the cabin. "We've got to know what's in that notebook before we leave this place. Let's have a look."

The boys quickly brought the book from its place of concealment and carried it to the table, where they bent eagerly over it as Bob turned the pages.

"It doesn't look like sense to me," complained Jimmy. "I never saw such a lot of fool words jumbled together."

"Yes, but something tells me there's method in this madness," said Bob, his brows knit as he concentrated on the problem before him. "Say, fellows!" he exclaimed, as sudden excitement gripped him, "do you remember those nights we were listening to our big set and we heard the mysterious messages? They were just a lot of words, and we couldn't make anything out of them at the time."

"You bet I remember!" exclaimed Joe. "I think I could even tell you most of the words. Why, there's some of them in that book, right now!"

"Exactly," replied Bob, nodding. "I remember them, too, and this must be the key to the code. My stars, what luck! Let's see how close we can recall the words we caught, and then we'll see if we can make sense of them with the help of this key."

"I'll tell you the words as I remember them, and you check me up,"

suggested Joe, and this they accordingly did.

Between them they managed to get it straight, just as they had heard it, "Corn-hay-six-paint-water-slow-sick-jelly."

"I think that's right," said Bob. "Anyway, we'll see if it comes right with the key. You read the words, Joe, and I'll find them in this notebook and you can write them down. Shoot the first one."

"Corn," said Joe.

Bob hunted rapidly down the columns of code words and their equivalents, and soon found the one he was after.

"Motor truck," he read out.

"That sounds promising!" exclaimed Joe. "The next word I've got is 'hay.' What's the answer to that?"

"Silk," said Bob, after a shorter search this time.

"Six," read Joe.

"Castleton Road!" exclaimed Bob, his voice shaking with excitement as he traced down the columns of words. Herb and Jimmy were also excited; especially the former, as he realized better than the others how serious a loss the theft of his father's truckload of silk had been and now thought he saw some clue in this message that might throw light on the whereabouts of the stolen goods.

CHAPTER XIX

THE ROBBERS' CODE

"The next word is 'paint,'" said Joe. "What does that stand for, Bob?"

"Just a minute, till I find it," replied his friend, and after turning over several pages found the word he sought.

"It means 'to-night,'" he said. "Read what we've got so far."

"Motor truck--silk--Castleton Road--to-night," read Joe. "That's clear enough so far. The next code word is water."

"'No guards,'" said Bob. And so they went, until the completed message read as follows:

"Motor truck--silk--Castleton Road--to-night--no guards--hold up--take everything to usual place--notify when job is done."

"That's the message that caused the theft of my father's merchandise!"

exclaimed Herb, jumping to his feet. "If we had only had the key then, when there was still time, we could have prevented the hold-up."

"Very likely we could," agreed Bob soberly. "But we may be able to do the next best thing, Herb--get the stuff back again. If we make a copy of this key and then leave the book just where we found it, the thieves will never dream that anybody knows their secret, and they'll keep right on using the same code."

"I see," said Herb slowly. "And then if we hear any more code messages we can translate them with this key, and likely get on the trail of the crooks."

"Exactly!" replied Bob. "Now, I have a notebook here, and if one of you fellows will dictate that code, I'll copy it down and we'll get out of here while the getting's good. There's no telling what minute some of the gang will show up."

"I'll dictate," volunteered Joe. "But while you and I are doing that, Bob, why can't Jimmy and Herb act as lookouts? Then if any of the gang comes along they can give us warning and we'll clear out."

"That's good advice," agreed Bob, and Herb and Jimmy went outside and up the path a short distance, where they crouched, listening, with every muscle tense to warn their comrades if danger threatened.

Meanwhile, in the cabin, Bob's pencil flew at furious speed as Joe dictated. The code was very complete, and consisted of over two hundred words, each word, in some cases, standing for a whole phrase. Bob wrote as he had never written before, but in spite of his utmost efforts it took over an hour to copy the entire list. He and Joe expected every minute to hear Herb or Jimmy give the alarm, but the woods remained calm and peaceful, and they finished their task without interruption.

"There's the last word, Bob!" exclaimed Joe, with a sigh of relief.

"Let's put that little book back on the shelf where we found it, and make a quick getaway."

"Yes, we've got to make tracks," agreed Bob. "It will be away after dark now when we get back to the camp. If we don't hurry they will be organizing searching parties for us."

With great care he placed the notebook back on the shelf, under the board, and then gazed searchingly around the cabin to make sure that no signs of their visit were left behind to warn the thieves. After a.s.suring himself that everything was exactly as they had found it, he and Joe left the rude habitation, snapping the big padlock through the hasp.

"That's a swell lock," observed Joe, grinning. "It looks strong enough to discourage anybody, but Jimmy's fish-hook licked it to a frazzle in no time."

"That's the way with a lot of padlocks," said Bob, as the two started off in search of the others. "It would take dynamite to break them open, but they're easy enough to pick."

"If you know how, that is," supplemented Joe, with a grin.

"Oh, that's understood," replied Bob. "It's hard to do anything without the know-how."

They soon picked up the two sentinels, who were greatly relieved to see them.

"I thought you were going to spend the night there," grumbled Jimmy.

"What happened? Did you both fall asleep in the middle of it?"

"You're an ungrateful rascal, Doughnuts," answered Joe. "Here Bob and I have worked like slaves for the last hour, while all you had to do was loaf around in the nice fresh air. Then instead of thanking us, you growl because we took so long."

"Well, don't get sore," protested Jimmy. "I suppose we should all be so happy over this discovery that we shouldn't mind anything. I'll bet your father will be tickled to death, Herb."

"I guess he will," agreed Herb. "Although we're still a long way from getting back the stolen silk. There's no doubt that we've struck a mighty promising clue, that much is sure."