“What are you going to do with us?” asked Tom.

“Never mind.  You came where you had no right to, and you must take the consequences.”

“We did have a right to come here!” exclaimed Mr. Jenks.  “I am entitled to know how the diamonds are made.  I paid for the information, and you tricked me.  If ever it’s possible I’ll have the whole gang arrested for swindling.”

“You’ll never get the chance!” declared Folwell.  “You were given some diamonds for the money you invested, and that makes us square.”

“No, it doesn’t!” declared Mr. Jenks.  “I invested the money to learn how to make diamonds, and you know it!  You tricked me, and I had a right to try to discover your secret!  I nearly have it, too, and I’ll get it completely before I’m done with you!”

“No, you won’t!” boasted Folwell.  “But we didn’t come here to tell you that.  We came to give you something to eat.  We’re not savages and we’ll treat you as well as we can in spite of the fact that you are trespassers.  We’re going to give you some grub, but I warn you that any attempt to escape will mean that some of you will get hurt.”

He signalled to some of his confederates.  These men unbound the captives’ arms, and stood over them while they ate some coarse food that was brought into the small cave.  They were given coffee to drink, and then, when the simple meal was over, they were securely bound again, and left to themselves, while the diamond makers went back to their machinery.

It was evident that they were going to attempt a big operation, for an unusually large quantity of the white stuff was prepared.  The prisoners watched them idly.  They could see some but not all of the operations.  In this way several hours passed.

Gloom possessed the hearts of Tom and his friends.  Not only had their expedition been almost a failure so far, but the young inventor was worried lest the gang might discover and wreck his airship.  This would prove a serious loss.  Lying there in the semi-darkness the lad imagined all sorts of unpleasant happenings.

At times he dozed off, as did the others.  They had become somewhat used to the pain caused by the bonds, for their nerves were numb from the strain and pressure.

Once, as he was lightly sleeping, Tom was awakened by hearing loud voices in the main cave.  He looked out, rolling over slightly to get a better view.  He saw the man who, once before had run in to give news of an approaching electrical storm.

“Are you fellows all ready?” asked this same man again.

“Yes.  Is there another storm coming?”

“Yes, and it’s going to be a corker!” was the reply.  “It’s one of the worst I’ve ever seen.  It’s sweeping right up the valley.  It’ll be here in an hour.”

“That’s good.  We need a big flash to make all the material we have prepared into diamonds.  It’s the biggest batch we ever tried.  I hope it succeeds, for we’re going to leave—­” The rest was in so low a tone that Tom could not catch it.