Looking closer in the darkness, however, Hal saw a slight opening at the bottom, the space between the rock and the ground being perhaps three feet.  The rock, apparently, rested upon more solid ground farther back.

“Follow me,” said the big man again.

He dropped on his hands and knees and wriggled through the opening.

At this point Stubbs manifested a desire to leave the others in the lurch.

“Say!” he exclaimed.  “You’re not going to get me under there.  How do you know what he may have in mind to do to us?”

“Come, Stubbs,” said Hal.  “Don’t be a quitter all the time.  Nothing is going to hurt—­”

Before he could finish his sentence he felt himself seized in a powerful grip from behind.  He twisted about with an effort and looked down upon the scowling face of Nikol.

“Here!  What’s the matter?” he cried.

The dwarf grinned at him evilly, and still retaining his hold, gazed at Stubbs.

“He insulted you,” he said.  “What shall I do with him?”

“Great Scott!  Let him down!” exclaimed the little man, anxiously.  “He didn’t do anything to me.”

“But he insulted you,” protested Nikol.  “I heard him say—­”

“Oh, that was just in fun,” cried Stubbs.  “Let him go.”

The dwarf’s hold relaxed and Hal jumped away.

“Don’t try any of that on me again,” he said, facing Nikol angrily.  He turned to Stubbs.  “You just instruct this fellow to keep his hands off me, or I shall have to take my gun to him.”

“Oh, he didn’t mean any harm,” Stubbs protested.

“Maybe he didn’t and maybe he did,” replied Hal.  “At any rate, I don’t like that kind of treatment.  You tell him what I said.”

“He was just sticking up for me,” said Stubbs, aggrievedly.  “But I’ll tell him.”

He did so, but the dwarf said nothing.

At this juncture the big Cossack poked his head from beneath the rock.

“Are you coming in here or not?” he demanded in a gruff voice.

“Coming,” said Hal, dropping to his knees.

“Look here, Hal,” said Stubbs, “I don’t like the looks of this place.  Maybe we had better stay outside.”

“Nonsense,” Edwards spoke up at this point.  “The man means us no harm.”

Hal had disappeared beneath the rock and Edwards dropped to his knees and crawled after him.

“Well,” said Stubbs to himself, “I don’t like this, but I guess I might as well go along.”

Motioning Nikol to follow him, he, too, dropped to all fours and crawled slowly beneath the big rock.

Beyond the rock, a brisk fire made dimly visible what appeared to be a large cavern.  The fire seemed to be in the exact center of a large underground room and beyond it Hal thought he could make out the mouths of dark passageways that led off in several directions.

“Come up to the fire and get warm,” the big Cossack invited.