With the coming of night he set forth, and Werper, who had scaled the cliffs alone behind the ape-man’s party, and hidden through the day among the rough boulders of the mountain top, slunk stealthily after him. The boulder-strewn plain between the valley’s edge and the mighty granite kopje, outside the city’s walls, where lay the entrance to the passage-way leading to the treasure vault, gave the Belgian ample cover as he followed Tarzan toward Opar.

He saw the giant ape-man swing himself nimbly up the face of the great rock. Werper, clawing fearfully during the perilous ascent, sweating in terror, almost palsied by fear, but spurred on by avarice, following upward, until at last he stood upon the summit of the rocky hill.

Tarzan was nowhere in sight. For a time Werper hid behind one of the lesser boulders that were scattered over the top of the hill, but, seeing or hearing nothing of the Englishman, he crept from his place of concealment to undertake a systematic search of his surroundings, in the hope that he might discover the location of the treasure in ample time to make his escape before Tarzan returned, for it was the Belgian’s desire merely to locate the gold, that, after Tarzan had departed, he might come in safety with his followers and carry away as much as he could transport.

He found the narrow cleft leading downward into the heart of the kopje along well-worn, granite steps. He advanced quite to the dark mouth of the tunnel into which the runway disappeared; but here he halted, fearing to enter, lest he meet Tarzan returning.

The ape-man, far ahead of him, groped his way along the rocky passage, until he came to the ancient wooden door. A moment later he stood within the treasure chamber, where, ages since, long-dead hands had ranged the lofty rows of precious ingots for the rulers of that great continent which now lies submerged beneath the waters of the Atlantic.

No sound broke the stillness of the subterranean vault. There was no evidence that another had discovered the forgotten wealth since last the ape-man had visited its hiding place.

Satisfied, Tarzan turned and retraced his steps toward the summit of the kopje. Werper, from the concealment of a jutting, granite shoulder, watched him pass up from the shadows of the stairway and advance toward the edge of the hill which faced the rim of the valley where the Waziri awaited the signal of their master. Then Werper, slipping stealthily from his hiding place, dropped into the somber darkness of the entrance and disappeared.

Tarzan, halting upon the kopje’s edge, raised his voice in the thunderous roar of a lion. Twice, at regular intervals, he repeated the call, standing in attentive silence for several minutes after the echoes of the third call had died away. And then, from far across the valley, faintly, came an answering roar—once, twice, thrice. Basuli, the Waziri chieftain, had heard and replied.

Tarzan again made his way toward the treasure vault, knowing that in a few hours his blacks would be with him, ready to bear away another fortune in the strangely shaped, golden ingots of Opar. In the meantime he would carry as much of the precious metal to the summit of the kopje as he could.

Six trips he made in the five hours before Basuli reached the kopje, and at the end of that time he had transported forty-eight ingots to the edge of the great boulder, carrying upon each trip a load which might well have staggered two ordinary men, yet his giant frame showed no evidence of fatigue, as he helped to raise his ebon warriors to the hill top with the rope that had been brought for the purpose.