“This is a secret passage leading to the palace,” Hakon explained hurriedly. “Its existence and the automatic trap-door entrance above us with its rebound feature alone has preserved our lives thus far. Lead on, Dyarkon.” The guard addressed, obediently led the way down the passage, the others following. Above, faint sounds of the conflict still raging seemed far away. Zola placed her hand in Robert’s trustfully. They had proceeded several rods when the emperor, who was second in lead, swayed uncertainly. He would have fallen but for Robert’s timely assistance. Zola also rushed to his side with a startled cry. “Ah, my children, I fear I am too badly wounded to go on. Leave me and escape while you may.” “We go on only with you, sire,” said Robert, firmly. Gently he and Professor Palmer lifted the protesting monarch between them. In this manner they resumed their march down the long passage, led by the faithful Dyarkon. Zola followed closely in the rear. In silence they made their way through the long tunnel beneath the city’s streets. Except for the shuffle of their feet, an oppressive, deathlike stillness reigned. At intervals Hakon begged them futilely to put him down and hurry on to safety without him. Though the passage led in almost direct line from the amphitheater to the palace, it was a considerable distance. The emperor was no slight burden and Robert’s muscles ached with the continued strain. In spite of his years, however, the professor seemed to be bearing his part of the monarch’s weight without great effort. A touch on his shoulder caused Robert to look round sharply. Zola was directly behind him, her hand upon his arm. “Wait!” she whispered, glancing apprehensively over her shoulder. Robert and Professor Palmer halted. Dyarkon, proceeding a few paces farther, also stopped as he perceived they were not following. “What is it?” Robert asked. His gaze followed hers down the dim passage stretching off behind them in ghostly emptiness. He failed to discern any cause for her uneasiness. “Listen! Did you not hear footsteps?” They all listened tensely. Only the beating of their own hearts disturbed the deadly underground quiet. An icy touch on his neck caused Robert to start. But he discovered that it was only a drop of water, fallen from the sweating roof. Here, possibly, was the origin of the sound which had startled Zola. Every little sound within the long tunnel was magnified a hundred times by the reverberation from the dead walls. The shuffling of a foot brought muffled shufflings from the farthest recesses of the passage, dying in soft, throbbing whispers that slipped from wall to wall faintly. “I thought I heard footsteps following us,” Zola explained a trifle shamefacedly, but with a little pucker of perplexity on her forehead. “Just the echoes, my dear,” said her father.