One of the Green Men beckoned to Gerry to follow him down a narrow flight of steps at the back of the room. It ended in a circular pool of water like a large well, the steps going on down below the surface. Their guide opened a cupboard built into the wall and took out four glass helmets. The helmets were attached to leather pads that fitted tightly about the shoulders and chest, with straps to hold them in place. A cylindrical metal tank was attached to the back of each helmet, with a tube that led to a valve at the side. The guide also took out some heavily leaded sandals. "Put on these helmets and then open the valves," he explained, "then follow me down the steps. Be careful not to fall in the darkness. After we get around the first bend in the corridor below there will be light." Gerry put the globular glass helmet over his head, opening the valve as soon as he had adjusted the straps. The air in the helmet immediately took on a faintly chemical odor, but it was pleasant and in no way oppressive. As soon as all of them were ready, the man called Slag beckoned and then started down the steps. Warm black water rose to Gerry's knees, then to his waist. As it came up to his shoulders he saw the top of Slag's helmet disappear below the surface ahead of him. For a moment the smooth surface of the water was level with Gerry's eyes as it rose around his own helmet. Then he stepped down into a darkness as black and impenetrable as though he were immersed in ink. Gerry guided himself with his left hand on the slime covered stones of the wall beside him. He reached back with his other hand to steady Closana who was just behind. All together he counted thirty steps, feeling carefully with his feet each time, before the floor leveled off. The wall curved around to the right. Gerry followed it, rounded a bend, and was no longer in darkness. They stood in a straight passage that was lined with blocks of polished stone. Metal plates, set in the ceiling at regular intervals, glowed with a greenish-yellow light that was nearly as bright as the cloudy Venusian daylight. The place was completely filled with water. It was an eerie sensation! Slag was standing a few feet ahead, grinning at them through the glass of his helmet, but now he turned and walked slowly down the corridor. Gerry followed him, bent well forward as he walked, forcing himself ahead against the resistance of the water. All their movements were sluggish and slow, but the heavily leaded sandals held them down and gave their feet purchase. * * * * *