But his words were interrupted by a hoarse cry bursting simultaneously from the throats of Jovians and Earthmen alike. "_Look!_" And turning once more to the screen, all witnessed the dreadful climax ... the end of the planet Mercury. For how long a time it had been tugging at its cosmic bonds none knew, but suddenly a critical point of balance was reached. With a great, impulsive leap the tiny planet burst free of its solar gyves. Like a gleaming stone hurled from some gigantic catapult it flashed outward from its orbit, writhing, shimmering, shaking. Then its flight altered. For the space of a long-drawn, tremulous breath it seemed to hang motionless in the void, ungoverned by any gravitational force or power of natural law ... then the immutable order of nature asserted itself. The laws of Mass-and-Distance asserted their claim. Like a fluttering moth drawn irresistibly to a flame, the fleeing world fell backward into its luminary. Faster and faster it raced, now dropping plummetlike toward the blazing prominences of Sol. As it fell it was squeezed and hammered out of shape by the tremendous forces playing upon it. For a moment it looked like a lengthening sphere ... then a teardrop ... then the pear-shape split into an infinitude of crushed and shapeless fragments which streaked like falling pebbles into the beckoning heart of Sol. For the briefest instant a faintly brighter flame seemed to flicker upon Sol's surface as the parent sun hungrily swallowed its infant. Then ... that was all. * * * * * Muldoon turned away, shuddering. He said in a dull, dazed voice, "There--there were men on that planet. Posts, mines, laboratories...." "Johnny Cosgrave," said Hugh Warren. "He would have finished his three years of foreign service next month. He was going back to Earth to get married." Gary said tightly, "What happened to Mercury will happen to _all_ the planets if we are not successful. That or something equally horrible. As the sun dwindles, its weight per volume will increase; all the inner planets will be devoured as was Mercury. "You--" He turned to the Jovian Councillor--"Your planet may not suffer that fate. You are too far away. But the sun's heat will fail, and when that happens cold will sweep down upon you ... such devastating cold as cannot be imagined. If your orbit widens, you may whirl away from the sun and be lost in the never-ending depths of space." The Councillor said gravely, "You need say no more, Earthman. I understand perfectly. We of Jupiter are sometimes hasty, but never fools. Say now, what do you need of us? How can we cooperate with you to stay this impending doom?" "Speed," said Lane. "The knowledge of that which your race alone knows: the secret of achieving speed faster than that of light."