Alondra produced from his pocket a little electric lamp, and by its aid they followed the passage for some distance. Then they came to more steps, which went much farther down into the ground. They also came to other side-passages, which branched off in different directions. Soon the passage became wider and higher, and finally ended in a heavily barred door, which, however, was standing ajar. They listened cautiously, and, hearing no one about, pushed it open, and suddenly found themselves in a blaze of light. Yet it was certain that they were not in the open air. They stared around, and then up, in wondering astonishment. They seemed to be in another glass-house, for certainly there was some kind of transparent or semi-transparent roof overhead. But the light was not the light of the sky exactly. It was a strange reflected light, such as puzzled the three who gazed at it. Then an idea flashed into Jack’s mind. ’I know what it is!’ he whispered. ’We are looking up through water! This place is built underneath the large lake in the gardens.’ ’Yes, you are right. It must be so,’ Alondra agreed. ’But why? This must be some place constructed in this strange fashion on purpose that its very existence should be kept a secret! Now, why is that, I wonder? I do not believe that my father even knows of its existence. But why all this secrecy? There seems to be no one about. Let us try to find out what it all means.’ One thing they found it undoubtedly was—a treasure-house. They quickly saw enough to convince them that Agrando had a great store of treasure here. But there were also roomy chambers, and a spacious central place, with a great dome as large as a good-sized theatre, and not unlike one, having banks of seats around, one behind the other, arranged like semicircular steps. The use of this building seemed very doubtful, as did that of some small, dark side-chambers—mere cells—of which there were quite a number about. While the explorers were wondering what it all meant, they heard the sound of voices. Jack pointed to one of the small cells high up in the wall, and led the way up the banks of seats, stepping from one to the other like going upstairs. The cell had a strong door, the upper part of which consisted of a grille, and when they were well inside they pulled it to after them. Then, peering through the grille, they could see nearly all over the interior. The voices drew nearer, and in a few moments there entered King Agrando, Kazzaro, and Zuanstroom, with two attendants, each of whom bore small sacks. Judging by their manner, the sacks were pretty heavy.