We were within some forty thousand miles of the moon. Giant white ball--all of its disc visible to the naked eye. It poised over the bow, and presently, as the Planetara swung upon her course for Mars, it shifted sidewise. The light of it glared white and dazzling in our tiny side windows. Snap, with his habitual red celluloid eyeshade shoved high on his forehead, worked over our instruments. "Gregg!" The receiving shield was glowing a trifle! Gamma rays were bombarding it! It glowed, gleamed phosphorescent, and the audible recorder began sounding its tiny tinkling murmurs. Gamma rays! Snap sprang to the dials. The direction and strength were soon obvious. A richly radio-active ore body, of considerable size, was concentrated upon this hemisphere of the moon! It was unmistakable. "He's got it, Gregg! He's--" The tiny helio mirrors began quivering. Snap exclaimed triumphantly, "Here he comes! By God, the message at last! Bar off that light!" * * * * * I flung on the absorbers. The moonlight bathing the little room went into them and darkness sprang around us. Snap fumbled at his instrument board. Actinic light showed dimly in the quivering, thumbnail mirrors. Two of them. They hung poised on their cobweb wires, infinitely sensitive to the infra-red light-rays Grantline was sending from the moon. The mirrors in a moment began swinging. On the scale across the room the actinic beams from them were magnified into sweeps of light. The message! Snap spelled it out, decoded it. "_Success! Stop for ore on your return voyage. Will give you our location later. Success beyond wildest hopes--_" The mirrors hung motionless. The shield, where the Gamma rays were bombarding, went suddenly dark. Snap murmured, "That's all. He's got the ore! 'Success beyond wildest hopes.' That must mean an enormous quantity of it available!" We were sitting in darkness, and abruptly I became aware that across our open window, where the insulation barrage was flung, the air was faintly hissing. An interference there! I saw a tiny swirl of purple sparks. Someone--some hostile ray from the deck beneath us, or from the spider bridge that led to our little room--someone out there trying to pry in! Snap impulsively reached for the absorbers to let in the outside light--it was all darkness to us outside. But I checked him. "Wait!" I cut off our barrage, opened our door and stepped to the narrow metal bridge. "Wait, Snap! You stay there." I added aloud, "Well, Snap, I'm going to bed. Glad you've cleaned up that batch of work." * * * * * I banged the door upon him. The lacework of metal bridges and ladders seemed empty. I gazed up to the dome, and forward and aft. Twenty feet beneath me was the metal roof of the cabin superstructure. Below it, both sides of the deck showed. All patched with moonlight.