Gianapolis lurched forward, his eyes glazing, half raised his arm--pointing back into the cave of the dragon--and dropped, face downward, on the floor, with a crimson pool forming slowly about his head. An unfamiliar sound had begun to disturb the silence of the catacombs. Max glanced at the white face of Helen Cumberly, then directed the ray of the little lamp toward the further end of the apartment. A steady stream of dirty water was pouring into the cave of the dragon through the open door ahead of him. Into the disc of light, leaped, fantastic, the witch figure of the Eurasian. She turned and faced him, threw up both her arms, and laughed shrilly, insanely. Then she turned and ran like a hare, her yellow silk dress gleaming in the moving ray. Inhaling sibilantly, Max leaped after her. In three strides he found his foot splashing in water. An instant he hesitated. Through the corridor ahead of him sped the yellow figure, and right to the end. The seemingly solid wall opened before her; it was another masked door. Max crossed the threshold hard upon her heels. Three descending steps were ahead of him, and then a long brick tunnel in which swirled fully three feet of water, which, slowly rising, was gradually flooding the cave of the dragon. On went the Eurasian, up to her waist in the flood, with Max gaining upon her, now, at every stride. There was a damp freshness in the air of the passage, and a sort of mist seemed to float above the water. This mist had a familiar smell.... They were approaching the river, and there was a fog to-night! Even as he realized the fact, the quarry vanished, and the ray of light from Max's lamp impinged upon the opening in an iron sluice gate. The Eurasian had passed it, but Max realized that he must lower his head if he would follow. He ducked rapidly, almost touching the muddy water with his face. A bank of yellow fog instantly enveloped him, and he pulled up short, for, instinctively, he knew that another step might precipitate him into the Thames. He strove to peer about him, but the feeble ray of the lamp was incapable of penetrating the fog. He groped with his fingers, right and left, and presently found slimy wooden steps. He drew himself closely to these, and directed the light upon them. They led upward. He mounted cautiously, and was clear of the oily water, now, and upon a sort of gangway above which lowered a green and rotting wooden roof. Obviously, the tide was rising; and, after seeking vainly to peer through the fog ahead, he turned and descended the steps again, finding himself now nearly up to his armpits in water. He just managed to get in under the sluice gate without actually submerging his head, and to regain the brick tunnel. He paused for a moment, hoping to be able to lower the gate, but the apparatus was out of his reach, and he had nothing to stand upon to aid him in manipulating it.