She flashed her light back on the way they had come, and as she did so she cried:

"It was the door. It has swung shut, girls! We're trapped!"

CHAPTER XXVIII-PRISONERS

Walter and Paul stood close beside Jack Kimball, as he turned over the package which had dropped from the automobile-Cora's automobile, to be exact.

"What is it?" asked Walter.

"Just what I'm going to find out," answered Jack. "Feels like a package of money, if I'm any judge."

"Whew!" whistled Paul. "Counterfeiters, do you think?"

"I'm not so rash as to do any thinking after the queer things that have been happening," retorted Jack. "I'm going to make sure before I do any guessing. Here goes!"

He cut the string of the packet. It was well wrapped in stout brown paper, and when Jack, sitting down on a wayside stone and resting the bundle on his knees, had folded back the covering, there was revealed to the boys bundles of tickets tied in little packets.

"What in the world is this?" asked Paul, picking up one of the little packages. "Tickets?"

"Railroad and theatrical," added Walter, as he examined some more closely. "Say, this is a queer find!"

Jack whistled shrilly and then cried out:

"It fits in! It all fits in!"

"What does he mean?" asked Paul.

"I don't know," Walter answered. "Tell us, Jack. Can you see through the puzzle?"

"Part of it. Don't you see? These tickets-some railroad and the others for theatres and opera houses-they're counterfeit-bogus-no good! They're just like those that girl in the Spinning Wheel tea room bought. Don't you remember, she purchased two of a couple of young fellows. It was thought at the time they might have been the ones who went off with Cora's auto. Now we reverse the process. We find the bundle of tickets that dropped out of Cora's car, and we see two men running away in it.

They're the same ones, or in the same gang, I haven't a doubt. It's up to us to get after them."

"You seem to have struck it," commented Walter. "Do you mean these men have gone into the business of counterfeiting tickets on as big a scale as this?"

"I'm thinking that," Jack answered. "You see it wouldn't pay to print a few tickets. They'd have to make a whole lot of them, and in the case of theatrical coupons, sell them quickly, for the fraud would soon be discovered. Railroad tickets might take a little longer to prove invalid, for they would have to go to the head offices, and there the railroad men could tell by the consecutive numbers that there was duplication somewhere. And the tickets would have to be pretty well distributed-only a few in each city."

"That's what they wanted of Cora's auto," suggested Paul. "They wanted to cover a big area."

"Yes," Jack went on. "And they probably have accomplices in many places.

Once the tickets were printed, they had to distribute them over a wide territory. Boys, I think we've discovered a daring band of ticket-counterfeiters."

"But where do they do their work-their printing?" asked Walter.

"Why not in the cave?" asked Jack. "It would be the most natural place around here."

"What's the matter with looking in that shack where the auto came from?"

asked Paul, nodding back toward the field against a hill in which the shed was built.

"I was going to suggest that," Jack went on. "Perhaps that is another entrance to the same cave Cora found. Come on, we'll have a look, anyhow. We've got this for evidence, in any case," and he held up the bundle of tickets.

"Are you sure they are bogus?" asked Paul.

"Well, not positive, of course," Jack said. "But you'd hardly find so many kinds of railroad and theatrical tickets, the latter for a number of different cities, all in one bundle unless something were wrong. I put these fellows down as counterfeiters of tickets, and you'll see I'm right."

"Well, we'll take a chance," decided Walter. "Now what are we going to do about getting Cora's car back?"

"We can't do much right away," said Jack. "But those fellows will come back, I'm sure. Let's explore a bit in that shack, and then we'll go and rip out that door in the secret pa.s.sage."

The doors of the shack which stood against the hill in the big field were fastened with a cheap padlock, and Jack, after a moment of hesitation, smashed it with a stone.

"Come on in, boys!" he called, swinging back the doors.

"It's as dark as pitch," complained Walter. "Did any of you bring your flash lamps?"

"Left 'em at the bungalow," Paul answered. "I have some matches though."

By the glimmer of one he struck, the boys saw that the shack was a sort of vestibule to a cave, for a big hole extended under the side of the hill.

"Jack was right!" Walter exclaimed. "This is a cavern, and it looks to be a good-sized one. I wish we had a light."

"Here's a lantern," said Paul, who had lighted another match. "We'll explore a bit."

By the greater light of the lantern, which was found near the doors, the boys saw that the cave was indeed a large one, extending well back under the hill. They went in cautiously at first, not knowing what they might find, or what hidden pitfalls might lie in their path.

"Look!" exclaimed Jack, pointing to several boxes lying about. "They must have been doing, or else are getting ready to do, lots of business.

Those boxes contain paper and cardboard by the looks and marks on them.

And now--"

"Hark!" exclaimed Paul in a whisper. They all listened. From somewhere far back in the cave came a dull, rumbling, vibrating noise, and the ground faintly trembled.

"There it is again!" said Walter-"that strange noise. Now we'll find out what it is. Come on."

He started forward, the others following, Paul in the rear with the lantern, for it had a reflector on and gave better light when carried behind the boys.

"Wait a minute!" cautioned Jack. "I don't seem to hear that noise now.

It's stopped."

"So it has," concurred Paul.

They listened intently, then Jack said:

"I hear another sound, though. It's behind us, toward the mouth of the cave. Boys, it's those fellows coming back. Out with that light, Paul.

We'll hide in here and surprise them. Quick! Down behind some of these boxes!"

Paul extinguished the lantern, and he and his companions sought places of concealment. They could now plainly hear footsteps approaching, while they also distinguished the murmur of excited voices.