almost at once, there was a new sound—a multiple throbbing, at a quick, snarling tempo that hinted at enormous power, growing louder each second. hradzka stiffened and drew his blaster; as he did, five more aircraft swooped over the crest of the mountain and came rushing down toward him; not aimlessly, but as though they knew exactly where he was. as they approached, the leading edges of their wings sparkled with light, branches began flying from the trees about him, and there was a loud hammering noise.

he aimed a little in front of them and began blasting. a wing flew from one of the aircraft, and it plunged downward. another came apart in the air; a third burst into flames. the other two zoomed upward quickly. hradzka swung his blaster after them, blasting again and again. he hit a fourth with a blast of energy, knocking it to pieces, and then the fifth was out of range. he blasted at it twice, but without effect; a hand-blaster was only good for a thousand yards at the most.

holstering his weapon, he hurried away, following the stream and keeping under cover of trees. the last of the attacking aircraft had gone away, but the little scout-plane was still circling about, well out of blaster-range.

once or twice, hradzka was compelled to stay hidden for some time, not knowing the nature of the pilot's ability to detect him. it was during one of these waits that the next phase of the attack developed.

it began, like the last one, with a distant roar that swelled in volume until it seemed to fill the whole world. then, fifteen or twenty thousand feet out of blaster-range, the new attackers swept into sight.

there must have been fifty of them, huge tapering things with wide-spread wings, flying in close formation, wave after v-shaped wave. he stood and stared at them, amazed; he had never imagined that such aircraft existed in the first century. then a high-pitched screaming sound cut through the roar of the propellers, and for an instant he saw countless small specks in the sky, falling downward.

the first bomb-salvo landed in the young pines, where he had fought against the first air attack. great gouts of flame shot upward, and smoke, and flying earth and debris. hradzka turned and started to run. another salvo fell in front of him; he veered to the left and plunged on through the undergrowth. now the bombs were falling all about him, deafening him with their thunder, shaking him with concussion. he dodged, frightened, as the trunk of a tree came crashing down beside him. then something hit him across the back, knocking him flat. for a moment, he lay stunned, then tried to rise. as he did, a searing light filled his eyes and a wave of intolerable heat swept over him. then darkness....

"no, zarvas pol," kradzy zago repeated. "hradzka will not return; the 'time-machine' was sabotaged."

"so? by you?" the soldier asked.

the scientist nodded. "i knew the purpose for which he intended it. hradzka was not content with having enslaved a whole solar system: he hungered to bring tyranny and serfdom to all the past and all the future as well; he wanted to be master not only of the present but of the centuries that were and were to be, as well. i never took part in politics, zarvas pol; i had no hand in this revolt. but i could not be party to such a crime as hradzka contemplated when it lay within my power to prevent it."

"the machine will take him out of our space-time continuum, or back to a time when this planet was a swirling cloud of flaming gas?" zarvas pol asked.

kradzy zago shook his head. "no, the unit is not powerful enough for that. it will only take him about ten thousand years into the past. but then, when it stops, the machine will destroy itself. it may destroy hradzka with it or he may escape. but if he does, he will be left stranded ten thousand years ago, when he can do us no harm.

"actually, it did not operate as he imagined and there is an infinitely small chance that he could have returned to our 'time', in any event. but i wanted to insure against even so small a chance."

"we can't be sure of that," zarvas pol objected. "he may know more about the machine than you think; enough more to build another like it. so you must build me a machine and i'll take back a party of volunteers and hunt him down."

"that would not be necessary, and you would only share his fate." then, apparently changing the subject, kradzy zago asked: "tell me, zarvas pol; have you never heard the legends of the deadly radiations?"

general zarvas smiled. "who has not? every cadet at the officers' college dreams of re-discovering them, to use as a weapon, but nobody ever has. we hear these tales of how, in the early days, atomic engines and piles and fission-bombs emitted particles which were utterly deadly, which would make anything with which they came in contact deadly, which would bring a horrible death to any human being. but these are only myths. all the ancient experiments have been duplicated time and again, and the deadly radiation effect has never been observed. some say that it is a mere old-wives' terror tale; some say that the deaths were caused by fear of atomic energy, when it was still unfamiliar; others contend that the fundamental nature of atomic energy has altered by the degeneration of the fissionable matter. for my own part, i'm not enough of a scientist to have an opinion."

the old one smiled wanly. "none of these theories are correct. in the beginning of the atomic era, the deadly radiations existed. they still exist, but they are no longer deadly, because all life on this planet has adapted itself to such radiations, and all living things are now immune to them."

"and hradzka has returned to a time when such immunity did not exist? but would that not be to his advantage?"

"remember, general, that man has been using atomic energy for ten thousand years. our whole world has become drenched with radioactivity. the planet, the seas, the atmosphere, and every living thing, are all radioactive, now. radioactivity is as natural to us as the air we breathe. now, you remember hearing of the great wars of the first centuries of the atomic era, in which whole nations were wiped out, leaving only hundreds of survivors out of millions. you, no doubt, think that such tales are products of ignorant and barbaric imagination, but i assure you, they are literally true. it was not the blast-effect of a few bombs which created such holocausts, but the radiations released by the bombs. and those who survived to carry on the race were men and women whose systems resisted the radiations, and they transmitted to their progeny that power of resistance. in many cases, their children were mutants—not monsters, although there were many of them, too, which did not survive—but humans who were immune to radioactivity."

"an interesting theory, kradzy zago," the soldier commented. "and one which conforms both to what we know of atomic energy and to the ancient legends. then you would say that those radiations are still deadly—to the non-immune?"

"exactly. and hradzka, his body emitting those radiations, has returned to the first century of the atomic era—to a world without immunity."

general zarvas' smile vanished. "man!" he cried in horror. "you have loosed a carrier of death among those innocent people of the past!"

kradzy zago nodded. "that is true. i estimate that hradzka will probably cause the death of a hundred or so people, before he is dealt with. but dealt with he will be. tell me, general; if a man should appear now, out of nowhere, spreading a strange and horrible plague wherever he went, what would you do?"

"why, i'd hunt him down and kill him," general zarvas replied. "not for anything he did, but for the menace he was. and then, i'd cover his body with a mass of concrete bigger than this palace."

"precisely." kradzy zago smiled. "and the military commanders and political leaders of the first century were no less ruthless or efficient than you. you know how atomic energy was first used? there was an ancient nation, upon the ruins of whose cities we have built our own, which was famed for its idealistic humanitarianism. yet that nation, treacherously attacked, created the first atomic bombs in self defense, and used them. it is among the people of that nation that hradzka has emerged."

"but would they recognize him as the cause of the calamity he brings among them?"

"of course. he will emerge at the time when atomic energy is first being used. they will have detectors for the deadly radiations—detectors we know nothing of, today, for a detection instrument must be free from the thing it is intended to detect, and today everything is radioactive. it will be a day or so before they discover what is happening to them, and not a few will die in that time, i fear; but once they have found out what is killing their people, hradzka's days—no, his hours—will be numbered."

"a mass of concrete bigger than this place," tobbh the slave repeated general zarvas' words. "the ancient spaceport!"

prince burvanny clapped him on the shoulder. "tobbh, man! you've hit it!"

"you mean...?" kradzy zago began.

"yes. you all know of it. it's stood for nobody knows how many millennia, and nobody's ever decided what it was, to begin with, except that somebody, once, filled a valley with concrete, level from mountain-top to mountain-top. the accepted theory is that it was done for a firing-stand for the first moon-rocket. but gentlemen, our friend tobbh's explained it. it is the tomb of hradzka, and it has been the tomb of hradzka for ten thousand years before hradzka was born!"