Frank's alarms were now very definitely excited. He could not understand the change in the man's policy in leaving the post which he had so steadfastly maintained in Lloyd's immediate proximity. He had either relinquished his scheme or he was now proceeding to put it into execution. Frank was mindful too of the malignity with which the mountaineer pointed the fact how his caution had overshot the mark by retaining the custody of the lantern. Much good would it do them if the guide, evidently curiously familiar with the place, should contrive to distance them altogether, or dodge behind one of the buttresses of the cliffs of this underground world, and so hiding leave them to find their way out of this labyrinth without a clue, or perchance, wandering in eccentric circles, perish finally of cold or starvation. It was impossible for them to recognise any landmark of the dread Plutonian scene—black night on every side, save dusky outlines of crags and chasms, the tiny white focus of the lantern with its fibrous halo failing in deep glooms, and beyond, the dim shadow of a man, trotting steadily—how well he knew his footing!—to lose sight of whom were certain death in this world of Erebus.
"If I only had a pistol, even without a cartridge in it, I'd stop that light-heeled fellow," Frank said indignantly, but in a low voice, over his shoulder to the two who followed close upon his steps.
"Don't be frightened, Miss Laniston," Lloyd reassured Lucia. "We shan't lose sight of our precious guide. I could run him down in two seconds. And if necessary I will just snatch you up in my arms and overhaul him forthwith. I'd do it now, but it is best to give him line, and see what his intentions really can be."
The next moment a chilly sound rang through the silent cave and all the unfortunate explorers started with a nervous shock. In another instant they recognised its character. It was the hooting of a screech-owl.
"That settles it," exclaimed Lloyd with a joyous sense of relief. "That shows we can't be very far from the outside. The owls hide about near the entrance of a cave in the daytime—then they fly out at night like the bats."
Lucia tried to share his hopefulness; she looked about with eager expectancy. "But I don't see or hear any bats," she said.
"They will no doubt put in an appearance before long," Lloyd answered. "There is the owl again."
She shivered at the blood-curdling, ill-omened cry, despite its fortunate augury to them.
The shrill, uncanny notes of the screech-owl again trembled repetitiously on the thin, rare air, then the low, sinister chuckling of the bird ensued, so true to life, so perfectly imitated that the cry had been several times repeated, after considerable intervals, before they perceived that they had heard no owl—that the mountaineer now and again paused as he hurried on in advance and standing still mimicked the creature's ill-omened cry with a perfection of similitude that might have deceived the senses of more practical woodsmen than they professed to be. The stoppage gave the explorers time to gain on their strange guide and as the shrilling rang out once more the source whence it emanated became obvious.
Frank, looking over his shoulder at the others, showed a startled, dismayed face and Lloyd with a strange, unaccustomed thrill about his heart, felt that a crisis impended. Their thought was the same—they were following a madman, or he was signalling to confederates ambushed in the hope of booty, or he was masking the noise of their approach by this, a familiar sound.