The contact with the Venus beam lasted a minute or two. Snap and I, on the cauldron rim, were engulfed in the blaze of reflected light and the wild scream of sound. Then presently the turmoil subsided. The contact in the sky was broken. The tow-rope of Venus jerked itself away. But on the next Venus rotation it would be attacked again. Another few minutes passed. The little circular depression beneath us was dim and silent as we had first seen it. Figures were moving within the dwelling structure. From several of the underground entrances figures came up, the ten-foot insect-like shapes of workers. Three or four of the brains came bouncing up, moving along the ground catwalk with little leaps. All the figures entered the distant main dwelling house. The contact was over. "Probably hardly anyone left down below," Snap whispered. "Now's our chance." "If we can get into that opening without being seen," I said. "Shadows, down the rocks to the left. Damnation, Gregg, we can make it in one calculated leap." "I'll try it first. I'll get in and wait for you." "Right." We each had a gravity cylinder at our belt and a ray-gun in our hand. The slope of the depression was dim here, merely starlit; it was a steep, broken and fairly shadowed descent, fifty feet to the little dome-like kiosk which marked the nearest subterranean entrance. I went down it with a swoop, landed in a heap beside the kiosk and ducked into it. Instinct made me fear a guard, but reason told me none would be here; there was only the danger of encountering someone coming up. I was at the top of a winding, descending passage, a step-terraced floor; there were occasional lights in the ceiling. In a moment Snap joined me. "Got here! I wonder how far down it goes?" I gripped him. "Snap, no matter what happens, do it with a rush. Keep with me. And if I shout to get out...." "We go out with a rush!" "Yes. Back to the girls. Use your ray-gun and the gravity projector in getting back to them and get away without me, if I fall." "Same for you, Gregg." We went down the deserted passage. We had had experience in movement on Wandl now; we handled ourselves more deftly. We went down several hundred feet. The passage branched, but there always seemed a main tunnel. It was all deserted. There were distant, dimly-lighted, silent rooms. Were these factories of the strange forms of electronic gravity currents Wandl used? Some were in operation. A hum issued from them. Workers moved about. We stopped to consult. The girls, and Molo himself, had described what we would find: a main route leading to the control room where the delicate mechanisms which operated all this were centralized, the nerve center of Wandl. It seemed that we were following that main route. A worker came with a swimming leap past us. We dropped into a hollowed shadow at a tunnel intersection, and he went swooping by. "Lord, Snap," I muttered, "that was too close for comfort."