They were soon on their way up the dizzy path once more, and, as they advanced, they found it growing more and more dangerous.  In some places they found it almost impossible to get around certain corners, where there was barely room for their feet.  As Tom remarked grimly, a fat man never could have done it.  Fortunately they were all comparatively thin, for their hard work, and not too abundant food, since they had left the airship, had reduced their weight.

Up and up they went, higher and higher, sometimes finding the path wide enough for two to walk abreast, and again seeing it narrow almost to a ribbon.  They hardly dared look down into the chasm at their left—­a chasm filled, in part, with the rocks and boulders tossed into it by the lightning bolt.

Tom was in the lead, and had just made a dangerous turn around a shoulder of rock—­one of those places where he had to extend both arms, and fairly hug the cliff before he could get around.

But, when he had made it, and found himself on a broad pathway, cut in the living rock, he gave a great shout—­a shout that caused his companions to hasten to his side.  They found the young inventor pointing to a clump of bushes and small trees.

But it was not the shrubbery that Tom desired to call to their attention.  They saw that in an instant, for, dimly seen through the leaves, was something black, and, as they looked more closely, they saw that it was a great hole in the side of the mountain—­a vast cavern, opening like a tunnel.

“The cave!  The cave!” cried Tom.  “The diamond makers’ cave!”

Hardly had he spoken than two men, each one carrying a gun, showed themselves in the mouth of the cavern, and, instant later they both ran toward the little party of adventurers.

CHAPTER XVII—­THE PHANTOM CAPTURED

Surprise held Tom and his friends almost spellbound for the moment.  The young inventor’s hand went toward the pocket where he carried his revolver.  Mr. Jenks, who had the only other weapon, sought to draw it, but he was stopped by a gesture of one of the two men with guns.

“Hold on, strangers!” the man cried.  “I know what you’re up to!  Better not try to draw anything—­it might not be healthy.  Now, then, who are you, and what do you want?”

The question came rather as a surprise, at least to Tom and Mr. Jenks.  They had taken it for granted that these men—­if they were the diamond makers—­would know Mr. Jenks, and guess at his errand in coming back to Phantom Mountain.  But, it seemed, that they took them all for casual strangers.

No one answered for a moment.  Tom caught the eye of Mr. Jenks, and there was a look of hope in it.  If ever there was a time for strategy, it was now.  Evidently Munson, the stowaway on the airship, had not yet been able to send a warning to his confederates.  And neither of the two men recognized Mr. Jenks as the man who had been defrauded of his rights.  It might be possible to conceal the real object of the adventurers until they had time to formulate a plan of action.