They were not in the cave over an hour when Michael appeared. He was quite nervous, and greatly troubled.

“We want you, Mr. Epworth,” he greeted, “to come and take command of the camp. Toplinsky has been carried off by the huge moon monsters of insect creation, and we are not able to contend with what may come up.”

“But suppose Toplinsky escapes and returns,” Joan objected. “Our heads will not be worth much.”

“We have threshed that out, and the camp will, as one man, force him to treat you kindly, and as an equal. In fact, they say that the Americans won the day for them against these Lunar enemies, and that hereafter they cannot afford to trust everything to the general. He will have to divide authority with you, and agree to your terms.”

“Very well. We will come. Billy, remain here and put things in shape to keep. We will not go off and leave ourselves without supplies in case we have to come back. Later we will return and all of us will go back to the Aerolite. I also think that we must band together to protect ourselves from all kinds of Lunar enemies.”

Accompanied by Joan, Epworth entered his glider and flew over to the Aerolite. They were greeted as conquering heroes, and Epworth was immediately put in charge of the camp. First, he established a strong military organization with Michael as the commanding officer, and arranged to materialize all the stores of the Aerolite into defense weapons. When this work was completed he created a council of five, and had the colonists elect the members. This council was to be the governing power, and he bound the pirates by firm obligations to force Toplinsky to obey the orders of this council.

With this accomplished he and Joan returned, well satisfied, to their cave, leaving the entire membership of the colony housed in the Aerolite so that if any danger arose they could fly out of it.

“Hey, there, Billy!” Epworth shouted as he landed lightly in front of the cave. “Snap out of it. We’re going to go to the Aerolite. From this on, I think it will be perfectly safe for us.”

There was no answer, and with a frown on his face the young man divested himself of his glider, and entered the cave.

Billy was not there, and his glider and all their supplies were missing.

“W-w-what do you suppose happened to him?” Joan inquired nervously, looking over Epworth’s shoulder. “We were not gone over two hours, and yet all of our supplies are gone—things that it took us ten days to cart from the Aerolite. Looks as if ghosts had been here.”

“Billy could not have moved them in this time,” Epworth reasoned. “Something has happened to him.”

With the carefulness of a detective he began to search the cave for evidence that would lead to the direction in which Billy had gone. Every article they had left in the way of supplies was gone. Even the water jars were missing, and the only evidence of the presence of enemies consisted of numerous small lines in the sand of the floor. These lines looked like finger marks. Billy’s foot prints, close to the point where they had last seen his glider, were plainly evidenced, but Epworth could not ascertain the direction he had gone when he left. In fact, reasoning by his foot tracks, he went up into the air, and he could not have gone far in this direction because the top of the cave would have stopped him.

Running back in the cave the young American looked for evidence that would indicate that the small finger tracks had gone that way. The back of the cave, which they had not previously investigated, ran up against a big pile of boulders and seemingly came to an end.

“These tracks,” he finally said to Joan in a hushed voice, “were probably made by those cricket-like animals that attacked the Aerolite. If so——”

“They have twelve hands and no feet. With their front hands they hold their weapons, and are also able to use their four leg hands as feet and hands.” She shivered. “It’s ghostly; it gives me the all-overs. They came in here, captured Billy and disappeared in the air.”

“I reason the same way,” Epworth agreed. “But what are we going to do? We must do something to help Billy.”

“Find out where they went and follow them.”

“Rather large order.” Epworth grinned dryly. “There may be two million of them.”

“They didn’t go back into the cave,” Joan insisted heatedly; “consequently they must have come up around the mountains and slipped up on Billy.”

“Then they discovered him while we were at the Aerolite, and have taken him to the northern range of hills—where they carried Toplinsky.”

“Sounds likely.”

“Then it is me for the north. You go to the Aerolite, and wait until I come back. I will make a thorough search in my glider.”

“Not me. Where you go I go also. I am not taking any chances of being separated from you in this strange world. To be candid I don’t like these cricket Things; and I don’t like the pigmy men who ride on them and direct them in battle.”

“Have it your way. We will communicate with Michael, and tell him to keep a constant watch, and that at the first approach of the enemies get into the air with the Aerolite. I am quite sure that in the airship they will be safe.”

But when they spoke to Michael and informed him that they contemplated going in search of Billy and Toplinsky, the young guard demurred.

“Suppose you discover them prisoners in the hands of a large army?” he suggested. “What will you do?”

“Scheme to free them. I certainly will not leave human beings at the mercy of myriads of cricket-shaped Things that may eat them.”

Equipped with food to last for a week, armed with tear guns and automatics, and carrying with them two large air helmets which they thought they might need in case they were forced to seek high altitude, they entered their gliders, and sailed toward the range of mountains in the north. There were many tall peaks ahead of them—mountains that stuck their noses high into the dark sky, and which Epworth knew were pitted with enormous craters.

When they got to the point where the cricket army had disappeared, they circled around for half an hour studying the country with their glasses. In front of them, near the range of mountains which they encircled, they saw another large valley, almost circular. Beyond this valley came a rugged foothill country and further on there was an immense peak, eighteen thousand feet high.

Epworth jockeyed his glider close to his sister.

“According to the maps of the earth astronomers,” he explained, “that mountain is the Crater Agrippa. I’ve got a hunch that our crickets dwell inside of that crater. It is deep down, over five miles, to the bottom, and if my reasoning is sound the air in the bottom of the crater is heavier than on the surface of the moon. It would, it seems, make an ideal place for Things like these crickets to live. They are thin of body, elongated in form, spread out broadly, light in weight but strongly muscled, and the gravity of the moon would about fit their physical shapes.”

“Granting all your science, what are you going to do?”

“Go to the bottom of that crater. If we find nothing there we will search among these innumerable small pits that we see everywhere.”

Joan shuddered.

“Go into the darkness of all these holes?”

She was terrified at the thought.

“Certainly—if we fail to find our friend above the hollows that we know are inside of the moon.”

“Hollows inside of the moon?” She dropped her eyes. She was startled, made afraid. The idea of crawling around on her hands and knees hunting for lunar crickets in dark holes was terrifying. “And—and—we must crawl in——?”

“I am more cheerful. These crickets were led by pigmy men. It is not likely that the pigmies live in holes, although, I am free to confess that I would naturally expect the crickets to be crawling around in dark places.”

With a slight shrug of her shoulders, Joan turned her glider toward the peak that Epworth had declared was the Crater Agrippa. In two minutes Epworth was in the lead. They were both determined, but their hearts were beating furiously.

What dangers would they meet deep in the bowels of the moon? What kind of life could they expect to find? Was Billy alive or dead? Had they taken him to join Toplinsky or would they have to make separate hunts for the two men?

To gain the summit of the high peak they had to go up in running jumps. They would run several steps, then jump into the air, and pedal to gain height. In this way they finally got to a point where they could look down into a deep crater.