"It is true! I go there. I not lie. I find the tunnel where we come--and it has gone!" "Impossible! What did you find?" "I not find it. It is true! I find there what this fellow say," he replied, turning savagely on Raoul. "It is--what you call?--one dead wall!" XIII MRS. QUAYLE TAKES THE LEAD Miranda was not dreaming--the tunnel had vanished. That may be a strong word for it; but anyway, whatever had happened, the tunnel was not to be found. Returning by the path upon which they had entered the subterranean chamber, they were confronted by a wall of rock where the entrance to the tunnel should have been. They were perfectly certain that when they passed out of the tunnel, less than half an hour before, into the main body of the cave, this wall had not been there. Where it had come from, why they had not seen it before, were posers too puzzling to waste time over. No one had seen it, of that they were certain; and they couldn't have helped seeing it if it had been there. Hence they were forced to the astonishing conclusion that this wall had moved into its present position during the last half hour through some invisible, superhuman agency. The whole thing, in fact, was incomprehensible, ridiculous, absurd. But there it was, for all that--and it had its depressing consequences. "You know that crocodile on the river," said Miranda impressively; "he open the mouth--the bird walk in. He shut the mouth--the bird is in one trap. So it is to us." Terrified by this picture of what had happened, Mrs. Quayle involuntarily clutched the jewels encircling her neck as if to protect them from some invisible brigand. The schoolmaster, also, seemed to suffer additional discomfort. Miranda's way of putting it, however, failed to satisfy the others. Leighton stoutly refused to believe in magic. Herran, in voluble Spanish, insisted that magic alone could explain the affair. Miranda repeated his alligator theory. "This cave is alive," he added. "You see the mark of the feets?" "Where is Mr. Arthur?" suddenly asked Una. They had been so absorbed in the mystery of the vanishing tunnel that the absence of one of their number had not been noticed. Una's startled query brought them face to face with another puzzle, as baffling and uncanny, in a way, as the wall of rock that had come from nowhere and planted itself between them and the entrance to the cave. Raoul had disappeared; search as they might, call as loudly as they could, no trace of him was to be found. Had he deliberately deserted them, or had he suddenly been spirited away by the same invisible agency that had prevented their leaving the cave? The more credulous of the party believed he had been spirited away. "But it is impossible," insisted Miranda angrily. "I see him now--and now he is not here. The canaille!" "There is only one thing to be done," declared Leighton emphatically. "We can't get out of here; we must go on." "Yes! Yes!" exclaimed Una.