It was with stronger forebodings than he dared acknowledge even to himself, that Professor Featherwit watched the two young men out of sight in the early gloom, and scarcely had his nephew passed beyond hearing than uncle Phaeton would gladly have recalled Bruno.

Waldo made light of all fears, prophesying complete success, and even going so far as to predict Bruno's return accompanied by the Children of the Sun; enthusiastic words which set the exile to trembling with excess of joy and anticipation.

What, then, was the blank dismay of all when, floating through the night, came the hollow throbbing of yonder mighty war-drum, fetching each person to his feet and holding him spellbound for the first few seconds.

Cooper Edgecombe turned sick at heart, even while ignorant as to the method of sending forth that alarm, his hollow groan being the first sound to follow the simultaneous exclamation which burst from three pairs of lips as the surprise came. And but a breath later Waldo broke forth with the excited query:

“What is it? What's broken loose now? Surely—thunder?”

Only Professor Phaeton at once recognised the sound, through description, and each one of those swiftly succeeding strokes seemed falling upon his heart, bidding him mourn for his beloved nephew, upon whom his aged eyes had surely looked their last in this life!

Yet it was the professor who took prompt action, speaking sharply as he darted across to where the air-ship rested:

“Come; get aboard, and let us do what lies in our power. It was criminal to send the poor lad into the jaws of death, but now—hasten, there may be a chance, even yet!”

The call was still hot upon his lips when his two companions entered the aerostat, gripping tight the hand-rail as Professor Featherwit sent the vessel afloat with reckless haste. As by a miracle they escaped disaster through rushing into a bushy treetop, and that fact served to steady the aeronaut's nerves.

“On guard, uncle Phaeton!” cried Waldo, making a lucky snatch at his cap, which one of the stiff boughs brushed off his head.

“Ay, ay, lad,” responded the man at the guiding-gear, as the air-ship shot onward and upward, now heading, as directly as was practicable, for the Lost City of the Aztecs. “That was the very lesson I needed. I am steady of nerve, now, and will show no lack,—heaven grant that we may not be for ever too late, though!”

“What do you reckon could have kicked up such a bobbery, uncle? And what—ugh!” as the wardrum's throbbings again swelled forth in grim alarm. “What in time is that, anyway?”

As briefly as might be, the professor explained, and almost for the first time Waldo felt a thrill of dread.

“If they've got Bruno, what will they do with him?”

That very dread was worrying uncle Phaeton, and already through his busy brain were flashing horrid pictures of punishment and sacrifice, of hideous scenes of torture, wherein the eldest son of his dead sister played a prominent role, perforce.

He dared not trust his tongue to make answer, just then, and sent the aeromotor onward at top speed, leaning far forward to win the earliest glimpse of—what?

He caught sight of blazing beacons fairly encircling the Lost City, forming a cordon through which no stranger could hope to pass unseen. He beheld hundreds of armed shapes rushing to and fro, plainly looking for some intruder or other enemy, yet almost as certainly failing as yet to make the longed-for discovery.

Not until that moment had uncle Phaeton dared indulge in even the shadow of a hope. The awful alarm seemed proof conclusive that poor Bruno had been taken, through the treachery of Ixtli.

Naturally enough, that was his first belief, but now, as the air-ship slackened pace to circle more deliberately above the valley, all eyes on the eager watch for either Bruno or something to hint at his fate, Professor Featherwit lost a portion of that conviction.

If Bruno had indeed fallen victim to misplaced confidence, and had been craftily lured into this den of ravening wild beasts, why all this confusion and mad skurry? Why had not the traitor first made sure of his victim? Why such a general alarm?

Although such haste in getting afloat had been made, some little time had been thus consumed, and, before the aerostat was fairly above the Lost City, Bruno and Ixtli had dropped by stages down the shadowed side of the Temple of the Sun God, to burrow underneath the ground as their surest method of eluding pursuit.

Only for that, the end might have been different, for, once sighted, Gillespie would have been rescued by his friends, or those friends would surely have shared death with him.

And so it came to pass that, circle though they might, calling ears to supplement their eyes, swooping perilously low down in their fierce eagerness to sight their imperilled one, never a glimpse of the young man could they obtain, nor even a definite hint as to where next to look for him.

“Surely they cannot have captured Bruno, as yet?” huskily muttered uncle Phaeton, hungrily straining his eyes without reward. “If the poor boy had actually fallen into such evil hands, why such crazy confusion? Why—oh, why did I permit his coaxings to overpower my better judgment? Why did I send him into—”

The words stuck in his throat and refused to issue. Phaeton Featherwit just then felt himself little less than a cold-blooded assassin.

Mr. Edgecombe was but little less deeply stirred, although his feelings were more of a mixture. He grieved for Bruno, and would willingly risk his life in hopes of doing the young man a service, yet his gaze was drawn far more frequently towards yonder temple, on the top of which he had—surely he HAD caught sight of his wife, his daughter!

“Let me down and try to find him,” he eagerly begged, as one might plead for a great boon. “I promise to save him if yet alive, and—let me try, professor; I beg of you, give me this chance to show my heartfelt gratitude.”

But Professor Featherwit shook his head in negation.

“That would only add to our trouble, friend. Knowing nothing of the dialect, you would be wholly at a loss. And, looking so entirely different in every respect, how could you hope to pass inspection?”

“All seems so confused, that I might—surely it is worth trying.”

“It would be suicidal, so say no more on that score,” almost harshly spoke the usually mild-mannered aeronaut, sending his vessel upon another circuit, only with stern vigilance choking back the appealing shout to his lost nephew.

This time the aerostat was brought directly above the Temple of the Sun, where there appeared to be some unusual disturbance, a number of armed guards fairly driving a gaily arrayed Indian down to the lower levels, and that greatly against his inclinations, judging from the harsh cries and ringing threats which burst from his lips.

Recognising the building, and unable to hold his intense emotions longer under stern control, Cooper Edgecombe called aloud the names of his wife and daughter, begging that they might come to him; but then the air-ship was sent onward and upward, with a dizzying swoop, and Professor Featherwit gripped an arm, sternly speaking:

“Quiet, sir! Another outbreak like that and I'll lock your lips, if I have to send a bullet through your mad brain!”

“I forgot. I could not wait longer, knowing that my loved ones—”

“You forgot that the lives of all depend upon our remaining at liberty,” coldly interrupted Featherwit. “Without this means of conveyance, how can your loved ones escape? Now, your solemn pledge to maintain utter silence, or I will take you back to yonder wilderness, leaving you to shift for yourself as best you can. Promise, sir!”

“I will,—I do. Forgive me, for I was carried away by—'twas there I saw—after so many horrible years!” huskily muttered the exile, fairly cowering there, before his saviour from the whirlpool.

“Enough; bear in mind that the rescue of your loved ones depend on our efforts. If discovered by yonder snarling beasts, and the machine is injured,—farewell, all hopes! Now, quiet, and look for Bruno!”

Again the air-ship circled over the valley, in spite of the moonlight passing wholly unseen and unsuspected by the Aztecs, whose energies were bent on ferreting out mortal foes, not demons of the upper world.

Waldo leaned farther over the hand-rail as they floated closer to an excited group of warriors, the central figure being Lord Hua himself, fiercely denouncing Aztotl and his son, Ixtli, as traitors to the common welfare, and calling upon all honest braves to mete forth befitting punishment.

Professor Featherwit caught one name indistinctly; that of the young Aztec in whose company Bruno had set forth on his ill-starred venture; and hoping to learn more of importance, he caused the aerostat to hover directly above that particular group of redskins.

Waldo, never stopping to count the risk he might thus fetch upon them all, silently lowered the grapnel, by means of the drag-rope, giving a boyish chuckle as the three-pronged hook descended amidst that gathering, the sight causing more than one superstitious brave to leap aside, with cries of amazed affright.

The air-ship gave a sudden swoop, and the grapnel caught Huatzin by his girdle, jerking him fairly off his feet, and swinging him into air, pretty much as a youngster might land a writhing fish. But no fish ever sent forth so wild a screech of mingled rage and terror as split the air just then.

Although hardly realising what was happening, Professor Featherwit sent the aeromotor upward with a mighty jerk. The shock proving too much for that sash, Lord Hua fell back to earth, literally biting the dust, although he met with no bodily harm beyond sundry bruises.

“Caught a sucker, and—I'll never do it again, uncle!” exploded Waldo, as he swiftly hauled in his novel fish-line; but he had to take a severe lecture from the professor before the subject was finally dropped.

And, worse than all else, the air-demon was now the target for both eyes and arrows, and, perforce, sailed swiftly away into the night.