All night Phobar watched the double mystery. By three o'clock, he was convinced, as far as lightning calculations showed, that the invader was hurtling toward the sun at a speed of more than ten million miles an hour. At three-fifteen, he thought that vanishing Neptune seemed brighter even than the band of fire running to the invader. At four, his belief was certainty. With amazement and awe, Phobar sat through the long, cold night, watching a spectacular and terrible catastrophe in the sky. As dawn began to break and the stars grew paler, Phobar turned away from his telescope, his brain awhirl, his heart filled with a great fear. He had witnessed the devastation of a world, the ruin of a member of his own planetary system by an invader from outer space. As dawn cut short his observations, he knew at last the cause of Neptune's brightness, knew that it was now a white-hot flaming sun that sped with increased rapidity away from the solar system. Somehow, the terrible swathe of fire that flowed from the dark star to Neptune had wrenched it out of its orbit and made of it a molten inferno. * * * * * At dawn came another bulletin from the Central Bureau. Neptune had a surface temperature of 3,000 deg. C, was defying all laws of celestial mechanics, and within three days would have left the solar system for ever. The results of such a disaster were unpredictable. The entire solar system was likely to break up. Already Uranus and Jupiter had deviated from their orbits. Unless something speedily occurred to check the onrush of the dark star, it was prophesied that the laws governing the planetary system would run to a new balance, and that in the ensuing chaos the whole group would spread apart and fall toward the gulfs beyond the great surrounding void. What was the nature of the great path of fire? What force did it represent? And was the dark star controlled by intelligence, or was it a blind wanderer from space that had come by accident? The flame-path alone implied that the dark star was guided by an intelligence that possessed the secret of inconceivable power. Menace hung in the sky now where all eyes could see in a great arc of fire! The world was on the brink of eternity, and vast forces at whose nature men could only guess were sweeping planets and suns out of its path.