CHAPTER

I A suspicious jeweler
II A midnight visit
III A strange story
IV Andy Foger gets A fright
V A mysterious man
VI Mr. Damon is on hand
VII Mr. Parker predicts
VIII off for the west
IX A warning by wireless
X dropping the stowaway
XI A weary search
XII the great stone head
XIII on phantom mountain
XIV warned back
XV the landslide
XVI the vast cavern
XVII the phantom captured
XVIII Bill Renshaw will help
XIX in the secret cave
XX making the diamonds
XXI flashing gems
XXII prisoners
XXIII broken bonds
XXIV in great peril
XXV the mountain shattered—­conclusion

CHAPTER I—­A SUSPICIOUS JEWELER

“Well, Tom Swift, I don’t believe you will make any mistake if you buy that diamond,” said the jeweler to a young man who was inspecting a tray of pins, set with the sparkling stones.  “It is of the first water, and without a flaw.”

“It certainly seems so, Mr. Track.  I don’t know much about diamonds, and I’m depending on you.  But this one looks to be all right.”

“Is it for yourself, Tom?”

“Er—­no—­that is, not exactly,” and Tom Swift, the young inventor of airships and submarines, blushed slightly.

“Ah, I see.  It’s for your housekeeper, Mrs. Baggert.  Well, I think she would like a pin of this sort.  True, it’s rather expensive, but—­”

“No, it isn’t for Mrs. Baggert, Mr. Track,” and Tom seemed a bit embarrassed.

“No?  Well, then, Tom—­of course it’s none of my affair, except to sell you a good stone, But if this brooch is for a young lady, I can’t recommend anything nicer.  Do you think you will take this; or do you prefer to look at some others?”

“Oh, I think this will do, Mr. Track.  I guess I’ll take—­”

Tom’s Words were interrupted by a sudden action on the part of the jeweler.  Mr. Track ran from behind the showcase and hastened toward the front door.

“Did you see him, Tom?” he cried.  “I wonder which way he went?”

“Who?” asked the lad, following the shopkeeper.

“That man.  He’s been walking up and down in front of my place for the last ten minutes—­ever since you’ve been in here, in fact, and I don’t like his looks.”