d over the autologs that recorded the ever-mysterious workings of the generator, punched test buttons on various electronic circuits, and in general went over the Mother from her square stern to her square bow. The inspections were made during the periods when Mother floated motionless in the blackness, less than a mote among the ever more dense fields of stars. After a charge things were a bit more interesting as Erin programmed blinks into the computer and punched them in one by one until the huge generator's charge was depleted. The little ship hurled itself down the star lanes toward the fiery heart of the galaxy. There came a time when the blinks were shorter, when the course became a zigzag made necessary by the density of the stellar population. Actual travel was instantaneous, but preparation for that travel began to take more and more time so that weeks became months. She had leisure during the charging periods for exploring the contents of the library, and for getting to know her companion. «You are, sir,» she said, as Moppy offered his right paw for shaking, «a rather remarkable fellow. You don't snore. You don't take up much of the bed. You know that your duty is to keep my feet warm at night and that all you're expected to do during the day is guard against boogers and to get a smile on your face and keep your big mouth shut. Men could learn a lot from you.» Moppy rolled over and said, «Uhhhhh,» which was his way of saying, «That's nice, Erin. Rub my stomach.» She was quite rapidly running out of charts. Winds of radiation swept past Mother as she floated in the hard, hard light of the crowded star fields. After each jump she was reminded of the difference between the Century Series of computers and the state-of-the art Unicloud aboard Rimfire. With millions of points of reference the old Century chuckled to itself for minutes before confirming position. There were times when Erin was tempted to cut the process short. She was, after all, still on established blink routes. However, from her first year at the Academy she had been taught to check and double-check. There was only one recorded case of it happening, but if some natural force, say the gravitational pull of an errant comet, had moved a blink beacon a substantial distance from its surveyed location, a ship using the coordinates of the beacon on which to base a blink might end up inside the atomic furnace of a star or become blended atom to atom with some small, dark body. As she moved ever deeper toward the star-packed core she began to develop a claustrophobic feeling of being hemmed in by stars: orange stars, red stars, blue-white stars; M stars and K stars; visual binaries and eclipsing binaries; variable stars—Cepheids and RR Lyrae stars, SS Cygni stars and R Corona Borealis stars; large stars and medium stars and blue giants and old, tired, dark, shrunken stars dead by nova in a time so remote that it was meaningless to a mere woman of New Earth who had the life expectancy promised to the men of Old Earth in the one surviving piece of Old Earth literature, the Bible. «The life span of man shall be a hundred and twenty years.» Genesis 6:3. She was just over one-quarter through her allotted time, if, indeed, she proved to be average; but as she jumped Mother carefully toward a dense cluster of New York type stars it seemed that time had slowed, that she would use up too much of her ration of years before Mother reached her destination. The New York cluster blocked a straight-line blink route into an area of space, less crowded among the harshness. The blink routes took her around the cluster and, the generator depleted, Mother was motionless in space within optic range of a small grouping of stars that were huddled together as if for company in a sort of cul-de-sac in space surrounded by glittering oceans of old, huge, central core monsters. The sac stars had families. One member of the planetary grouping of the star nearest her came onto her view screen when she punched orders into the computer. The world was one of several that had given mankind the shivers for centuries. Planets were not common enough to be ignored. Planets among the dense star fields near the core, some 10,000 light-years from the U.P. sector, were even more rare. Any ship coming into the sac would take a close look at the world known as D.W. One, and would see one principal reason why man had constructed huge fleets of ships and had armed them with the most deadly weapons that technology could supply. D.W. One, the first of the Dead Worlds to be encountered by a ship coming in from the periphery, had been killed with a totality that belied the difficulty of the feat. Man could denude a planet of forests, eliminate thousands of animal species, poison the atmosphere and the oceans with his wastes, but it was pretty damned difficult to kill a planet and leave it intact. A planet buster could fragment a world and leave nothing more than a belt of asteroids, but what had been done to the Dead Worlds was even more impressive, for D.W. One and several of her sister planets in the sac were dead from the inside out. Although she was old, she should have had a molten core. That she did not was one of the mysteries that had kept astrophysicists guessing and caused all U.P. exploration ships to go armed. If the planet killers ever came sweeping in from the vastness of space, man, so fragile in his frame of bones, tendons, cartilage, and flesh, would need protection. Thus, on Rimfire and on all other major ships of the X&A fleet there were weapons that could fragment a world if necessary. Once the planets in the sac had lived. Although there were no clues to the identity of the race or races that had peopled the Dead Worlds, unidentifiable rubble on the ravaged surface of D.W. One proved that there had been a technological civilization there. Now even the top soil was gone. The ground up nonbiodegradable debris of a technological civilization was scattered over a surface that was nothing more than inert rock. And into a flat, continent-sized area of the rock the killers, the race that had destroyed twenty living planets, had carved a warning. The message was not in words, but in symbols. An eye. A world, a stylized building and other, more obscure images. There was disagreement as to the exact words intended, but all of the experts agreed that the message carved into the bones of a continent was a warning: «Look at this world and tremble. Build not, for we will return.» Erin turned off the optics, shivered. Then, perversely, as if to prove to the vast emptiness around her that she wasn't really spooked by the mystery of twenty dead worlds, she checked the library index and watched a docu-history that told of the initial discovery of the worlds in the sac, and ended with the account of the last licensed scientific expedition to the sac by six graduate students aboard the Paulus, under Laconius of Tigian. The Paulus had disappeared, had vanished as completely as the race that had lived on the Dead Worlds. Every holo-drama fan could name the six students who had disappeared with Paulus. Of course, ships did evaporate into the nothingness of space from time to time, but the fact that the Paulus had disappeared while on a trip to the Dead Worlds had inspired writers, good and bad, to go into spasms of speculative creativity. Aside from the Dead Worlds docu-history, the Mother's library contained no less than three holo-dramas based on the loss of the Paulus. Erin watched two of them while waiting for the generator to charge and then, before the big power source was fully ready, she blinked onward and past the sac into the star fields and to the end of the line, as far as established blink beacons were concerned. From there on she had only the star chart in Mother's computer, a chart compiled by her father's old shipmate who, she felt, may or may not have known a black hole from his own dusky posterior orifice. She wanted a fully charged generator. She watched the third holo-drama about the Dead Worlds in which a rather sick minded writer presented the theory that giant lava beetles had hatched deep down in the fiery magma of the interior of the planets and had eaten the life from within before, in desperate hunger, they had emerged to crumble into tiny, unidentifiable bits everything they didn't eat. To get the taste of that one out of her mind, she selected the documentary version of the X&A expedition to the colliding galaxies in Cygnus and the finding of the Miaree manuscripts written in the language of the second alien race, the Artonuee, of which U.P. explorers had found evidence. She told herself that she'd had enough thinking about aliens, about planet killers and the Cygnus races who joined each other in death. She had spent her time of awe and wonder as an undergraduate, speculating with others on the nature of the female ruled Artonuee and the very masculine Delanians, and about the nature and the source of power for those who had devastated the Dead Worlds. But back in college on New Earth she'd been a long way from either the colliding galaxies in Cygnus or from the twenty worlds in the sac. Out here, alone except for a polite, gentle little dog, surrounded by the eternal glow of the core worlds, the possibility of coming face to face with the planet killers was a bit more real. Look on this world and tremble. Build not, for we shall return. With a fully charged generator she double-checked the visuals, ran a deep-search with all available ship's instruments, and, holding her breath, took the first blink from coordinates on the star chart drawn by her father's old shipmate. She and the ship arrived. As she prepared for the next jump, Mop came to her and politely asked to be held. She took him into her lap. «You're nervous, too?» she asked. He licked her thumb. Just once. «Don't blame you, little buddy,» she said. «But hang in there, huh?» She poised her finger over the button. «Heeeeeere we go.» After the little wrench to the system that is standard with a blink, she