They were trapped! * * * * * Standing there tense, speechless, they waited, wondering what would be the next move of this strange enemy who held them now so surely in his power. Nor had they long to wait. Almost immediately, there issued a gurgling sound from the inclined gallery, and turning their eyes in the direction of this new phenomena, they saw that the water level was receding, as though under pressure from above. "Singular!" muttered Professor Stevens. "A sort of primitive lock. It seems incredible that human creatures could exist down here, but such appears to be the case." Larry had no desire to dispute the assumption, nor had Diane. They stood there as people might in the imminence of the supernatural, awaiting they knew not what. Swiftly the water receded. Now it was scarcely up to their waists, now plashing about their ankles, and now the room was empty. The next moment, there sounded a rush of feet--and down the gallery came a swarm of the strangest beings any of them had ever seen. They were short, thin, almost emaciated, with pale, pinched faces and pasty, half-naked bodies. But they shimmered with ornaments of gold and jade, like some strange princes from the realm of Neptune--or rather, like Aztec chieftains of the days of Cortes, thought Larry. Blinking in the glare of the searchlights, they clamored around their captives, touching their pressure-suits half in awe and chattering among themselves. * * * * * Then one of them, larger and more regally clad than the rest, stepped up and gestured toward the balcony. "They obviously desire us to accompany them above," said the professor, "and quite as obviously we have little choice in the matter, so I suggest we do so." "Check!" said Larry. "And double-check!" added Diane. So they started up, preceded by a handful of their captors and followed by the main party. The gallery seemed to be leading toward the center of the pyramid, but after a hundred feet or so it turned and continued up at a right angle, turning twice more before they arrived at length in another stone chamber, smaller than the one below. Here their guides paused and waited for the main party. There followed another conference, whereupon their leader stepped up again, indicating this time that they were to remove their suits. At this, Professor Stevens balked. "It is suicide!" he declared. "The air to which they are accustomed here is doubtless at many times our own atmospheric pressure." "But I don't see that there's anything to do about it," said Larry, as their captors danced about them menacingly. "I for one will take a chance!" And before they could stop him, he had pressed the release-valve, emitting the air from his suit--slowly, at first, then more and more rapidly, as no ill effects seemed to result. Finally, flinging off the now deflated suit, he stepped before them in his ordinary clothes, calling with a smile: