Five minutes later I was whirling downward through the building's interior in one of the automatic little cone-elevators, out of which I stepped into a long white corridor. An attendant was awaiting me there, and I followed him down the corridor's length to a high black door at its end, which he threw open for me, closing it behind me as I stepped inside.
It was an ivory-walled, high-ceilinged room in which I found myself, its whole farther side open to the sunlight and breezes of the green gardens beyond. At a desk across the room was sitting a short-set man with gray-streaked hair and keen, inquiring eyes, and as I entered he sprang up and came toward me.
"Ran Rarak!" he exclaimed. "You've come! For two days, now, we've been expecting you."
"We were delayed off Aldebaran, sir, by generator trouble," I replied, bowing, for I had recognized the speaker as Hurus Hol, chief of the Bureau of Astronomical Knowledge. Now, at a motion from him, I took a chair beside the desk while he resumed his own seat.
A moment he regarded me in silence, and then slowly spoke. "Ran Rarak," he said, "you must have wondered why your ship was ordered back here to the solar system. Well, it was ordered back for a reason which we dared not state in an open message, a reason which, if made public, would plunge the solar system instantly into a chaos of unutterable panic!"
He was silent again for a moment, his eyes on mine, and then went on. "You know, Ran Rarak, that the universe itself is composed of infinite depths of space in which float great clusters of suns, star-clusters which are separated from each other by billions of light-years of space. You know, too, that our own cluster of suns, which we call the Galaxy, is roughly disklike in shape, and that our own particular sun is situated at the very edge of this disk. Beyond lie only those inconceivable leagues of space which separate us from the neighboring star-clusters, or island-universes, depths of space never yet crossed by our own cruisers or by anything else of which we have record.
"But now, at last, something has crossed those abysses, is crossing them; since over three weeks ago our astronomers discovered that a gigantic dark star is approaching our Galaxy from the depths of infinite space-a titanic, dead sun which their instruments showed to be of a size incredible, since, dark and dead as it is, it is larger than the mightiest blazing suns in our own Galaxy, larger than Canopus or Antares or Betelgeuse-a dark, dead star millions of times larger than our own fiery sun-a gigantic wanderer out of some far realm of infinite space, racing toward our Galaxy at a velocity inconceivable!
"The calculations of our scientists showed that this speeding dark star would not race into our Galaxy but would speed past its edge, and out into infinite space again, passing no closer to our own sun, at the edge, than some fifteen billion miles. There was no possibility of collision or danger from it, therefore; and so though the approach of the dark star is known to all in the solar system, there is no idea of any peril connected with it. But there is something else which has been kept quite secret from the peoples of the solar system, something known only to a few astronomers and officials. And that is that during the last few weeks the path of this speeding dark star has changed from a straight path to a curving one, that it is curving inward toward the edge of our Galaxy and will now pass our own sun, in less than twelve weeks, at a distance of less than three billion miles, instead of fifteen! And when this titanic dead sun passes that close to our own sun there can be but one result. Inevitably our own sun will be caught by the powerful gravitational grip of the giant dark star and carried out with all its planets into the depths of infinite space, never to return!"
Hurus Hol paused, his face white and set, gazing past me with wide, unseeing eyes. My brain whirling beneath the stunning revelation, I sat rigid, silent, and in a moment he went on.
"If this thing were known to all," he said slowly, "there would be an instant, terrible panic over the solar system, and for that reason only a handful have been told. Flight is impossible, for there are not enough ships in the Galaxy to transport the trillions of the solar system's population to another star in the four weeks that are left to us. There is but one chance-one blind, slender chance-and that is to turn aside this onward-thundering dark star from its present inward-curving path, to cause it to pass our sun and the Galaxy's edge far enough away to be harmless. And it is for this reason that we ordered your return.
"For it is my plan to speed out of the Galaxy into the depths of outer space to meet this approaching dark star, taking all of the scientific apparatus and equipment which might be used to swerve it aside from this curving path it is following. During the last week I have assembled the equipment for the expedition and have gathered together a force of fifty star-cruisers which are even now resting on the roof of this building, manned and ready for the trip. These are only swift mail-cruisers, though, specially equipped for the trip, and it was advisable to have at least one battle-cruiser for flag-ship of the force, and so your own was recalled from the Federation fleet. And although I shall go with the expedition, of course, it was my plan to have you yourself as its captain.
"I know, however, that you have spent the last two years in the service of the Federation fleet; so if you desire, another will be appointed to the post. It is one of danger-greater danger, I think, than any of us can dream. Yet the command is yours, if you wish to accept it."
Hurus Hol ceased, intently scanning my face. A moment I sat silent, then rose and stepped to the great open window at the room's far side. Outside stretched the greenery of gardens, and beyond them the white roofs of buildings, gleaming beneath the faint sunlight. Instinctively my eyes went up to the source of light, the tiny sun, small and faint and far, here, but still-the sun. A long moment I gazed up toward it, and then turned back to Hurus Hol. "I accept, sir," I said.
He came to his feet, his eyes shining. "I knew that you would," he said, simply, and then: "All has been ready for days, Ran Rarak. We start at once."
Ten minutes later we were on the broad roof, and the crews of our fifty ships were rushing to their posts in answer to the sharp alarm of a signal bell. Another five minutes and Hurus Hol, Dal Nara and I stood in the bridgeroom of my own cruiser, watching the white roof drop behind and beneath as we slanted up from it. In a moment the half-hundred cruisers on that roof had risen and were racing up behind us, arrowing with us toward the zenith, massed in a close, wedge-shaped formation.
Above, the brilliant signals of the traffic-boats flashed swiftly, clearing a wide lane for us, and then we had passed through the jam of traffic and were driving out past the incoming lines of interstellar ships at swiftly mounting speed, still holding the same formation with the massed cruisers behind us.
Behind and around us, now, flamed the great panorama of the Galaxy's blazing stars, but before us lay only darkness-darkness inconceivable, into which our ships were flashing out at greater and greater speed. Neptune had vanished, and far behind lay the single yellow spark that was all visible of our solar system as we fled out from it. Out-out-out-rocketing, racing on, out past the boundaries of the great Galaxy itself into the lightless void, out into the unplumbed depths of infinite space to save our threatened sun.
II
Twenty-four hours after our start I stood again in the bridgeroom, alone except for the silent, imperturbable figure of my ever-watchful wheelman, Nal Jak, staring out with him into the black gulf that lay before us. Many an hour we had stood side by side thus, scanning the interstellar spaces from our cruiser's bridgeroom, but never yet had my eyes been confronted by such a lightless void as lay before me now.