The storm messenger departed.  Folwell and Munson busied themselves about the machinery.  Tom dozed off again, dimly wondering what had become of Bill Renshaw, and whether the former ghost knew of their plight.  The others were asleep, as the young inventor saw by the dim light of a lantern in the cave.  Then, he too, shut his eyes.

Tom was suddenly awakened by feeling some one’s hands moving about his clothing.  At first he thought it was one of the diamond-making gang, who had sneaked in to rob him.  “Here!  What are you up to?” exclaimed Tom.

“Quiet!” cautioned a voice.  “Are you all here?”

“All of us—­yes.  But who are you?”

“Easy—­keep quiet, Tom Swift!  I’m Bill Renshaw!  I’ve been searching all over for you, since I got back to your cave and found it empty.  Now I’m going to free you.  I got in here by a secret entrance.  Wait, I’ll cut your ropes.”  There was a slight sound, and an instant later Tom was freed from his bonds.

CHAPTER XXIV—­IN GREAT PERIL

The young inventor could scarcely believe the good luck that had so unexpectedly come to him and his companions.  No sooner was Tom able to move freely about than Bill Renshaw performed the same service for Mr. Jenks and the others, cautioning them to be quiet as he awakened them, and cut the ropes.

“Bless my circulation!” exclaimed Mr. Damon, in a hoarse whisper.  “How did you ever get here.  I’d given ourselves up for lost.”

“Oh, I came in off the mountain, as there’s a big storm due,” explained the man.  “There was no need of me playing the haunt in daytime, anyhow.  I went to the cave, found you and your things gone, and I surmised that you might have walked into some trap.”

“We did,” admitted Mr. Jenks, grimly.

“Well, I hunted around until I found you,” went on Bill.  “This mountain is honeycombed with caves, all opening from the large one, I know them better than these fellows do, so I could explore freely, and keep out of their sight.  They didn’t know that there was a second entrance to this place, but I did, and I made for it, when I couldn’t find you in some of the other caves where I looked.  And, sure enough, here you were.”

“Well, we can’t thank you enough,” said Mr. Parker.  “But you say there is a big storm coming?”

“One of the biggest that’s been around these parts in some time,” replied Bill.

“Then perhaps the mountain will be destroyed,” went on the scientist, as calmly as if he had remarked that it might rain.

“I hope nothing like that happens until we get away,” spoke Mr. Damon, fervently.

“What had we better do?” inquired Tom.

“Get away, unless you want to discover some more of their secrets,” advised Bill.  “Those fellows are planning something, but I can’t find out what it is.  They are suspicious of me, I think.  But they are up to something, and I believe, it would be best for you to leave while you have the chance.  It may not be healthy to stay.  That’s why I did my best to untie you.”