And out of this had arisen my mission now. Mercury--the quicksilver of commerce--so recently come to tremendous value through its universal use in the new antiseptics which bid fair to check all human disease--was being produced in Nareda. The import duty into the United States was being paid openly enough. But nevertheless Hanley's agents believed that smuggling was taking place. It was to investigate this condition that Hanley was sending me. I had introduction to the Nareda government officials. I was to consult with Hanley by ether-phone in seeking the hidden source of the contraband quicksilver, but, in the main, to use my own judgment. A mission of diplomacy. I had no mind to pry openly among the people of these Lowland depths, looking for smugglers. I might, indeed, find them too unexpectedly! Over-curious strangers are not welcomed by the Lowlanders. Many have gone into the depths and have never returned.... I was above the Nares Sea, by midnight. I was still flying a thousand feet over the zero-height. Twenty-one thousand feet below me lay the black expanse of water. The moon had climbed well toward the zenith, now. Its silver shafts penetrated the hanging mist-stratas. The surface of the Nares Sea was visible--dark and sullen looking. I shifted the angles of incidence of the wings, re-set my propeller angles and made the necessary carburetor adjustments, switching on the supercharger which would supply air at normal zero-height pressure to the carburetors throughout my descent. I swung over Nareda. The lights of the little village, far down, dwarfed by distance, showed like bleary, winking eyes through the mists. The jagged recesses of the Mona valley were dark with shadow. The Nares Sea lay like some black monster asleep, and slowly, heavily panting. Moonlight was over me, with stars and fleecy white clouds. Calm, placid, atmospheric night was up here. But beneath, it all seemed so mysterious, fantastic, sinister. My heart was pounding as I put the Wasp into a spiral and forced my way down. CHAPTER II _The Face at the Window_ With heavy, sluggish engines I panted down and came to rest in the dull yellow glow of the field lights. A new world here. The field was flat, caked ooze, cracked and hardened. It sloped upward from the shore toward where, a quarter of a mile away, I could see the dull lights of the settlement, blurred by the gathered night vapors. The field operator shut off his permission signal and came forward. He was a squat, heavy-set fellow in wide trousers and soiled white shirt flung open at his thick throat. The sweat streamed from his forehead. This oppressive heat! I had discarded my flying garb in the descent. I wore a shirt, knee-length pants, with hose and wide-soled shoes of the newly fashioned Lowland design. What few weapons I dared carry were carefully concealed. No alien could enter Nareda bearing anything resembling a lethal weapon.