'And thus easily,' murmured Ivanta, with, a sigh—'thus simply are all my elaborate and complicated defences to be set at nought and overcome—laughed at, in fact! However, so be it! 'Tis a good plan; and if it succeeds, the possession of such a stronghold, with its machinery and underground waterfall, will be a piece of good fortune indeed.'

'And we will take good care,' said Alondra, laughing, 'to have that back entrance well guarded in future. Now, I want to be one of your party, friend Fumenta. That will suit me better than waiting about with the rest till some one else, having done all the fighting, opens the door to us.'

At this Gerald and Jack and their party asked to be allowed to go with Alondra, and pressed their claims so eagerly that at last Ivanta acceded.

'I shall myself make one,' he said. 'And since you so much desire it, you shall all join.'

Later on, the fleet of airships divided into two bodies, and one, the smaller portion, made direct for the heights of the mountain in which the stronghold was situated. The rest were to wait about till the time should come for making their presence known by a direct frontal attack.

Fumenta led his section into a small cave, which opened out, first into a gallery, and then into a spacious grotto. All were provided with small glow-lamps, ropes, metal staples for climbing, and other requisites, in addition to their arms, which consisted of tridents, shields, and the usual swords or spears.

The grotto had several galleries running out of it, and selecting one of these, Fumenta followed its windings for some distance, till he came to a small stream running into a deep cutting. A little farther on, this little watercourse took a sudden turn and disappeared into a hole on the left.

'That,' said the outlaw chief, 'is all that is left of the stream which formerly completely filled the tunnel it here plunges into. Nowadays you can walk along its bed and the water will not in any place reach to your knees.'

'How do you know?' Ivanta asked.

'I have traversed the whole distance,' was the answer. 'I even climbed up the sides of the well to see whether it was fenced off in any way, and I found it quite open. Moreover, the place where I emerged was empty and deserted. One could see it is never used now.'