Between the frozen wastes of the night side and the searing inferno of the dayside, the Twilight Belt held all that was Human on the tiny world of Mercury, Hell Planet of the Solar System. A strange world, airless, subject to the alien distortions of Einsteinian mathematics, Mercury was both a promise and a challenge, for here could be found torrents of cheap power essential to the ships and men in space. Lee Correy, Commander of the Station, plunges...