Peter Zveri established his camp on the edge of the forest at the foot of the barrier cliff that guards the desolate valley of Opar. Here he left his porters and a few askaris as guards and then, with his fighting men, guided by Kitembo, commenced the arduous climb to the summit.

None of them had ever come this way before, not even Kitembo, though he had known the exact location of Opar from one who had seen it; and so when the first view of the distant city broke upon them they were filled with awe, and vague questionings arose in the primitive minds of the black men.

It was a silent party that filed across the dusty plain toward Opar; nor were the blacks the only members of the expedition to be assailed with doubt, for in their black tents on distant deserts that Arabs had imbibed with the milk of their mothers the fear of jân and ghrôl and had heard, too, of the fabled city of Nimmr, which it was not well for men to approach. With such thoughts and forebodings were the minds of the men filled as they approached the towering ruins of the ancient Atlantean city.

From the top of the great boulder that guards the outer entrance to the treasure vaults of Opar a little monkey watched the progress of the expedition across the valley. He was a very much distraught little monkey, for in his heart he knew that his master should be warned of the coming of these many Gomangani and Tarmangani with their thundersticks; but fear of the forbidding ruins gave him pause, and so he danced about upon the top of the rock, chattering and scolding. The warriors of Peter Zveri marched right past and never paid any attention to him; and as they marched, other eyes were upon them, peering from out of the foliage of the trees that grew rank among the ruins.

If any member of the party saw a little monkey scampering quickly past upon their right, or saw him clamber up the ruined outer wall of Opar, he doubtless gave the matter no thought; for his mind, like the minds of all his fellows, was occupied by speculation as to what lay within that gloomy pile.

Kitembo did not know the location of the treasure vaults of Opar. He had but agreed to guide Zveri to the city, but, like Zveri, he entertained no doubt but that it would be easy to discover the vaults if they were unable to wring its location from any of the inhabitants of the city. Surprised, indeed, would they have been had they known that no living Oparian knew either of the location of the treasure vaults or of their existence and that, among all living men, only Tarzan and some of his Waziri warriors knew their location or how to reach them.

"The place is nothing but a deserted ruin," said Zveri to one of his white companions.

"It is an ominous looking place though," replied the other, "and it has already had its effect upon the men."

Zveri shrugged. "This might frighten them at night, but not in broad daylight; they are certainly not that yellow."

They were close to the ruined outer wall now, which frowned down upon them menacingly, and here they halted while several searched for an opening. Abu Batn was the first to find it—the narrow crevice with the flight of concrete steps leading upward. "Here is a way through, Comrade," he called to Zveri.