Oracle by David Wood, Sean Ellis

later.”
    “ Or the conquistadors got it,” said Jade. “Maybe our friend back there got trapped by the cave in after his buddies took the Moon stone.”
    Professor held up the leather bound book he had taken from the mummified corpse. “Might be something about that in here.”
    “ As much as I’d love to stop for story time, I think maybe that will have to wait until we’re out of here.”
    “ Seconded,” replied Professor, tucking the journal away again in a pocket. “Incidentally, at the risk of being labeled a pessimist again, has anyone else noticed that we seem to be going down?”
    Jade whipped her head around, pointing her light back in the direction they had come. In the fifteen minutes or so that they ’d been walking, there view had not changed much, but she certainly had not been aware of a change in elevation. Looking back, she could not tell if they were actually going down or not. “Are you sure?”
    “ Trust me, I’ve humped up and down enough hills to recognize the difference. It’s slight, but we’re lower now than when we started.”
    After considering this news for a moment, Jade shook her head. “It doesn’t change anything. This is the only way to go. The builders must have followed the course of a naturally occurring passage when they cut this tunnel, but we can see the evidence that they were here all around us. It has to go somewhere.”
    “ You’re assuming that it leads back to the surface,” Professor replied. “What if they used that shaft in the pyramid to get in? What if this was their passage to the Underworld?”
    “ Well, we can’t very well go back, can we? Instead of always playing devil’s advocate, why don’t you limit yourself to constructive comments?”
    Professor shrugged and, evidently unable to offer anything useful, lapsed back into silence. A few minutes later, he was proved right. Half right, at least.
    The passage had continued its gradual decline for perhaps another half-mile, during which time Jade began to hear a sound like white noise.
    “ Running water?” suggested Professor. “We must be near an underground river.”
    He said nothing more, perhaps worried that his statement might be misinterpreted as defeatism, but it soon became evident that the source of the sound was indeed water moving through the surrounding rock, and they were getting closer to it with each step.
    The passage abruptly opened into a cavern that would have been considered large by any standard, except compared to the expansive chamber where they had found the model of the solar system. Unlike that vast but austere hall, this cavern bore clear evidence, not merely of use by the ancients, but inhabitation.
    They found themselves in what appeared to be a temple complex devoted to the Great Goddess. The deity, in all her spidery glory, had been carved into the wall in such a way that the goddess ’ mouth was the tunnel entrance; they had, in a manner of speaking, been vomited out of her mouth. Water fountained from several other openings in the wall, which had been incorporated into the sculpture as well, each one situated at the end of one the goddess’ eight limbs.  The water collected into six-foot wide channels that framed a rectangular courtyard below the dais upon which they now stood. On either side of the courtyard, just beyond the waterways, were long stone steps that looked remarkably like the bleachers in a stadium. Looking down, Jade could see that the floor of the courtyard was not a flat surface, but sloped gently from each side, like an inverted pyramid, meeting at a narrow trough—about a foot wide and six feet long—in the center. Scattered around the courtyard, at intervals which appeared almost random, were a dozen carved stelae—stylized human-animal hybrids that gazed out with fierce expressions—and everywhere the floor was pock-marked with tiny holes about an inch in diameter.
    “ Could that be your missing Moon stone?” asked Professor,