"I will go, effendi," answered the Arab.
McGrath nodded in appreciation, and began to scan the trees about him. Presently he found what he was looking for—a faint blaze on a huge cypress, an old mark, almost imperceptible. Confidently then, he stepped into the marsh beside the tree. He himself had made that mark, long ago. Scummy water rose over his shoe soles, but no higher. He stood on a flat rock, or rather on a heap of rocks, the topmost of which was just below the stagnant surface. Locating a certain gnarled cypress far out in the shadow of the marsh, he began walking directly toward it, spacing his strides carefully, each carrying him to a rock-step invisible below the murky water. Ali ibn Suleyman followed him, imitating his motions.
Through the swamp they went, following the marked trees that were their guide-posts. McGrath wondered anew at the motives that had impelled the ancient builders of the trail to bring these huge rocks from afar and sink them like piles into the slush. The work must have been stupendous, requiring no mean engineering skill. Why had the Indians built this broken road to Lost Island? Surely that isle and the cave in it had some religious significance to the red men; or perhaps it was their refuge against some stronger foe.
The going was slow; a misstep meant a plunge into marshy ooze, into unstable mire that might swallow a man alive. The island grew out of the trees ahead of them—a small knoll, girdled by a vegetation-choked beach. Through the foliage was visible the rocky wall that rose sheer from the beach to a height of fifty or sixty feet. It was almost like a granite block rising from a flat sandy rim. The pinnacle was almost bare of growth.
McGrath was pale, his breath coming in quick gasps. As they stepped upon the beach-like strip, Ali, with a glance of commiseration, drew a flask from his pocket.
"Drink a little brandy, effendi," he urged, touching the mouth to his own lips, oriental-fashion. "It will aid you."
McGrath knew that Ali thought his evident agitation was a result of exhaustion. But he was scarcely aware of his recent exertions. It was the emotions that raged within him—the thought of Constance Brand, whose beautiful form had haunted his troubled dreams for three dreary years. He gulped deeply of the liquor, scarcely tasting it, and handed back the flask.
"Come on!"
The pounding of his own heart was suffocating, drowning the distant drum, as he thrust through the choking vegetation at the foot of the cliff. On the gray rock above the green mask appeared a curious carven symbol, as he had seen it years ago, when its discovery led him and Richard Ballville to the hidden cavern. He tore aside the clinging vines and fronds, and his breath sucked in at the sight of a heavy iron door set in the narrow mouth that opened in the granite wall.
McGrath's fingers were trembling as they swept over the metal, and behind him he could hear Ali breathing heavily. Some of the white man's excitement had imparted itself to the Arab. McGrath's hands found the three knobs, forming the apices of a triangle—mere protuberances, not apparent to the sight. Controlling his jumping nerves, he pressed them as Ballville had instructed him, and felt each give slightly at the third pressure. Then, holding his breath, he grasped the bar that was welded in the middle of the door, and pulled. Smoothly, on oiled hinges, the massive portal swung open.