“Whether they make for heaven or the other place, we’ll follow them as long as there is a follow left in us,” answered Mortimer grimly. For some twenty miles the mysterious craft kept its way, then, still at the same altitude, suddenly described a great semicircle, and laid a course due south. “What are they up to now?” questioned Mortimer. “Blessed if I know,” replied the Professor. “It looks very much as if we were going back the way we came.” “Curious!” commented Mortimer. “I suppose we can only follow and await developments.” “That’s all,” assented the Professor. The opinion expressed by Professor Dean that they were returning over practically the same course proved to be correct. Back they went for some twenty miles, and then the pursued began to descend, followed, of course, by their obstinate pursuers. The occupants of “The Royal Dean” perceived they were dropping into a great valley, shut in on all sides by towering mountain tops. “It seems we are to make a landing at last,” remarked Mortimer, scanning the valley beneath. There was no reply to this remark. Mortimer turned leisurely to address the Professor again, but was startled to see the latter staring with dilated eyes into space. “See!” he gasped. “There! Ah, and there!” Mortimer looked in the direction indicated and was dumbfounded to perceive to the westward, slightly above them, another air-ship bearing down. “Look over there!” exclaimed the Professor, pointing to the East. Mortimer shifted his glance to another air-ship. An instant later two more appeared, the one to the North and the other, beyond the line of the pursued air-ship, to the South. “We’re surrounded,” gasped the Professor, amazed. “What’ll we do? Try to escape? I fear, though, it will be useless, judging from the speed which I see they develop.” “Useless or not,” replied Mortimer obstinately, “we started out to follow that air-ship and follow it we will to the bitter end.” Even as they spoke, the four air-ships were rapidly closing in upon them and they could see that they were several times the size of the “Royal Dean” and that they carried a number of men. As they drew nearer, they saw what appeared to be miniature cannon protruding from their quarters. An instant later the air-ship to the West came within hailing distance. A man stepped to the prow and shouted something which they did not clearly hear. “They evidently want to speak to us,” said Dean, and he slowed down and came to a stop. The air-ship to the West also checked its speed, but still kept slowly approaching. The other three air-ships were fast closing in. “Why did you stop?” asked Mortimer with some annoyance. “We don’t want to let those fellows get away from us.” He nodded in the direction of the pursued. “No fear,” answered the Professor. “They are descending straight into the valley.” “Hello!” shouted Mortimer to the air-ship to the West. “Hello!” came back the answer. “Who are you?”