Police copters appeared abruptly. Long overdue, too. They hovered between the buildings, no more than a hundred feet up and the whirr of their rotors sent a chilling draft upon us. I watched the dull gray nozzles extrude from the white globular bellies above us; then came the first spurts of the antiriot foam. The Apocalyptists seemed to welcome it. They rushed forward, trying to get into position under the nozzles; some of them stripped off what few garments they wore and bathed in it. The foam came bubbling down, expanding as it met the air, forming a thick viscous soapiness that filled the street and made movement almost impossible. Moving now in angular jerks like machines running down, the demonstrators lurched to and fro, fighting their way through the layers of foam. Its taste was oddly sweet. I saw a girl get a jolt of it in the face and stumble, blinded, mouth and nostrils engulfed in the stuff. She fell to the pavement and disappeared totally, for by now at least three feet of foam rose from the ground, cool, sticky, cutting all of us off at our thighs. Vornan knelt and drew the girl back into view, although she would not suffocate where she was. He cleared the foam tenderly from her face and ran his hands over her moist, slippery flesh. When he gripped her breasts, her eyes opened and he said quietly to her, “I am Vornan-19.” His lips went to hers. When he released her, she scrambled away on her knees, burrowing through the foam. To my horror I saw Vornan was without his mask.

We could scarcely move at all, now. Police robots were in the street, great shining domes of metal that buzzed easily through the foam, seizing the trapped demonstrators and hustling them into groups of ten or twelve. Sanitation mechs were already out to suck up the excess foam. Vornan and I stood near the outer border of the scene; slowly we sloshed through the foam and reached an open street. No one seemed to notice us. I said to Vornan, “Will you listen to reason now? Here’s our chance to get back to the hotel without any more trouble.”

“We have had little trouble so far.”

“There’ll be big trouble if Kralick finds out what you’ve been up to. He’ll restrict your freedom, Vornan. He’ll keep an army of guards outside your door and put a triple seal on it.”

“Wait,” he said. “I want something. Then we can go.”

He darted back into the mob. By now the foam had hardened to a doughy consistency, and those in it were wallowing precariously. In a moment Vornan returned. He was dragging a girl of about seventeen who seemed dazed and terrified. Her costume was of transparent plastic, but flecks of foam were clinging to it, conveying a probably unwanted modesty. “Now we can go to the hotel,” he said to me. And to the girl he whispered, “I am Vornan-19. The world does not end in January. Before dawn I will prove it to you.”

We did not have to sneak back into the hotel. A cordon of searchers had spread out for blocks around it; within moments after we had escaped from the foam, Vornan tripped an identity signal and some of Kralick’s men picked us up. Kralick was in the hotel lobby, monitoring the detector screens and looking half berserk with anxiety. When Vornan strode up to him, still tugging the quivering Apocalyptist girl, I thought Kralick would have a fit. Blandly Vornan apologized for any trouble he might have caused and asked to be conducted to his room. The girl accompanied him. I had an uncomfortable session with Kralick when they were out of sight.

“How did he get out?” he demanded.

“I don’t know. He gimmicked the seal on his room, I suppose.” I tried to persuade Kralick that I had meant to give an alarm when Vornan left the hotel, but had been prevented by circumstances beyond my control. I doubt that I convinced him, but at least I got across to him the fact that I had done my best to keep Vornan from becoming involved with the Apocalyptists, and that the entire exploit had been none of my doing.

There was a noticeable tightening of security in the weeks that followed. In effect, Vornan-19 became the prisoner and not merely the guest of the United States Government. Vornan had been more or less an honored prisoner all along, for Kralick had suspected it was unwise to let him move about freely; but aside from sealing his room at night and posting guards, no attempt had been made to exert physical restraint on him. Somehow he had coped with the seal and drugged his guards, but Kralick prevented a repetition by using better seals, self-tripping alarms, and more guards.

It worked, in the sense that Vornan did not go on any further unauthorized expeditions. But I think that that was more a matter of Vornan’s own choice than of Kralick’s added precautions. After his experience with the Apocalyptists, Vornan seemed to subside considerably; he became a more orthodox tourist, looking at this and that but holding back his more demoniacal comments. I feared this subdued version of our guest the way I would fear a quiescent volcano. But in fact he committed no new outrageous transgressions of propriety, stepped on no toes, was in many ways the model of tact. I wondered what he was storing up for us.

And so the weeks of the tour dragged on. We looked at Disneyland with Vornan, and although the place had been visibly refurbished, it plainly bored him. He was not interested in seeing synthetic reconstructions of other times and other places; he wanted to experience the United States of 1999 at first hand. At Disneyland he paid more attention to the other customers than to the amusements themselves. We swept him through the park unheralded, moving in a small close-knit group, and for once he attracted little attention. It was as if anyone who saw Vornan at Disneyland assumed that what he saw was part of the park, a clever plastic imitation of the man out of time, and passed by with no more than a nod and a smile.

We took him to Irvine and showed him the trillion-volt accelerator. That was my idea: I wanted a chance to get back to the campus for a few days, to visit my office and my house and be sure that all was still well. Letting Vornan near the accelerator was something of a calculated risk, I thought, remembering the havoc he had produced at Wesley Bruton’s villa; but we saw to it that Vornan never came within reach of any of the control equipment. He stood beside me, gravely watching the screens, as I smashed atoms for him. He seemed interested, but it was the superficial interest a child might have shown: he liked the pretty patterns.

For a moment I forgot everything except the joy of manipulating the huge machine. I stood at the operating panel, with billions of dollars of equipment stretching above and before me, pulling switches and levers with the same glee Wesley Bruton had displayed while making his house work wonders. I pulverized atoms of iron and sent neutrons spraying madly about. I sent a stream of protons along the track and cut in the neutron injector so that the screen was spattered with the bright bursts of demolition lines. I conjured up quarks and antiquarks. I went through my entire repertoire, and Vornan nodded innocently, smiling, pointing. He could have deflated me as he had done the Stock Exchange man, simply by asking what the point of all this cumbersome apparatus might be, but he did not. I am not sure if his restraint was a matter of courtesy toward me — for I flattered myself that Vornan was closer to me than to any of the others who traveled with him — or if it was simply that for the moment his vein of impishness was played out, and he was content to stand and watch respectfully.

We took him next to the fusion plant on the coast. Again, this was my doing, though Kralick agreed it might be useful. I still had hopes, however flickering, of squeezing from Vornan some data on the energy sources of his era. Jack Bryant’s too-sensitive conscience spurred me on. But the attempt was a failure. The manager of the plant explained to Vornan how we had captured the fury of the sun itself, setting up a proton-proton reaction within a magnetic pinch, and tapping power from the transmutation of hydrogen to helium. Vornan was permitted to enter the relay room where the plasma was regulated by sensors operating above the visible spectrum. What we were seeing was not the raging plasma itself — direct viewing of that was impossible — but a simulation, a re-creation, a curve following peak for peak every fluctuation of the soup of stripped-down nuclei within the pinch tank. It had been years since I had visited the plant myself, and I was awed. Vornan kept his own counsel. We waited for disparaging remarks; none came. He did not bother to compare our medieval scientific accomplishments with the technology of his own age. This new Vornan lacked bite.