"No, ah, Captain, I can assure you it's not." He stumbled a little over the honorific. "Norms, especially in the New York area, had pretty well had to accustom themselves to the ways of aces, especially those who chose to emulate the comic-book heroes of yore and don colorful costumes. And Cap'n Trips was weirder than most."

"Tezcatlipoca's a nickel-iron oblong roughly a kilometer by a kilometer and a half, weighing a good many million metric tons. Depending on the angle at which it struck, it could create devastating tidal waves and earthquakes, it could produce effects such as those hypothesized for a nuclear winter, it could quite conceivably crack the crust or blow away much of the atmosphere. It would almost certainly be the greatest catastrophe in recorded history-I might give you a better estimate if I took time to work it all out on paper."

"But I won't. Because it's not going to hit the planet." He sipped coffee from a cracked mug. "Poor Fred."

"I admit I was rather startled that you spoke so sympathetically of him when I called you, Dr. Berg," Tachyon said. Berg set the cup down, stared at the tepid black surface. "Fred and I went to MIT together, Doctor. We were roommates for a year."

"But I thought everybody said Dr. Warren was just some kind of crackpot," Trips said.

"That's what they say. And he was a crackpot, much as I hate to say it., But he was not just any crackpot."

"I fail to see how a trained scientist could espouse the theories for which Dr. Warren was so, ah-"

"Notorious, Doctor. Go ahead and say it. You sure you won't have any coffee?" They refused politely. Berg sighed. "Fred had what you call a will of iron. And he had a romantic streak. He always felt there should be fantastic things out there-ancient astronauts, alien machines on the moon, creatures unknown to science. He wanted to be the first to go out and rigorously prove so many things respectable scientists scoffed at." His mouth slipped into a sad smile. "And who knows? When Fred and I were kids, people thought the idea of intelligent life on other planets was farfetched. Maybe he could have pulled it off."

"But Fred was impatient. When he didn't see the results he wanted-why, he started seeing them anyway, if you know what I mean."

"So it was as Dr. Sagan said in his article in the Times," Tachyon said, "Dr. Warren fastened upon a rock which falls by the Earth at regular intervals and embued it with menace."

Berg frowned. "With all due respect, Dr. Sagan got it wrong this time. Gentlemen, Dr. Warren had an infinite capacity for self-deception, but he wasn't just some fool the Informer dragged in off Seventh Avenue. He knew how to use an ephemeris, was surely cognizant of 1954C-1100's history."

"He was a trained astronomer, and as far as technical and observational details go, a damned fine one." He shook his shaggy head. "How he could talk himself into believing this nonsense about Tezcatlipoca, God alone knows."

Trips was polishing his glasses on his fantastic bow tie. "Any chance he could've been right, man?"

Berg laughed. "Forgive me, Captain. But Tezcatlipoca's newest approach was spotted and plotted eight months ago by Japanese astronomers. It does in fact intersect the Earth's orbital path, but well clear of the planet itself "

He stood up, smoothed down his sweater, which had ridden up to the center of his stomach. "That's the pity, gentlemen. Oh, not this"-patting incipient paunch-"but the disservice Fred performed his fellow scientists. Our instruments are so much more sophisticated than they were even last time Tezcatlipoca passed, in 1970. And yet any astronomer who dares twitch his telescope in its direction will wind up lumped with von Daniken and Velikovsky forevermore."

The night was well advanced. Tach was sitting slumped in a chair in his apartment in a maroon smoking jacket and semidarkness, listening to Mozart in violins, bibbing brandy, and getting far gone in maudlin when the phone rang.

"Doe? It's me, Mark. I've found something."

The tone in his voice cut through brandy fog like a firehose. "Yes, Mark, what is it?"

"I think you better come see for yourself."

"On my way."

Fifteen minutes later he was on the floor above the Cosmic Pumpkin, gaping around in stoned amazement. "Mark? You have a whole laboratory above your head shop?"

"It's not complete, man. I don't have any real big-scale stuff, no electron microscopes or anything. Just what I was able to piece together over the years."

It looked like a cross between Crick amp; Watson and a hippie crash pad circa 1967, shoehorned into a space barely larger than a broom closet. Diagrams of DNA strands and polysaccharides shared wall with posters of the Stones, Jimi, Janis, and, of course, Mark's hero Tom Marion Douglas, the Lizard King-a twinge here for Tach, who still blamed himself for Douglas's death in 1971. A Terrestrial biochemist's tools were more familiar to Tach than an astronomers, so he recognized here a centrifuge, there a microtome, and so on. A lot of it had obviously seen hard use before passing into Trips's hands, some was jerry-rigged, but it all looked serviceable. Mark was in a lab coat, looking grim. "`Course, I didn't need anything too fancy, once I saw the gas chromatography on that tissue sample."

Tach blinked and shook his head, realizing the large and convolute piece of equipment whose identity he'd been puzzling over the last half-minute was possibly the world's most intricate bong. "What did you find, then?" he demanded. Mark passed him a slip of paper. "I don't, like, have enough data to confirm the structure of that protein chain. But the chemical composition, the proportions…"

Tachyon felt as if a coin were being dragged down the vertebrae in his neck. "Swarmling biomass," he breathed. Mark gestured at a bale of papers stacked on a bench. "You can check the references on this, analyses from the Swarm invasion. I-"

"No, no. I trust your work, Mark, more than anyone's but mine." He shook his head. "So swarmlings murdered Dr. Warren. Why?"

"How about how, man? I thought swarmlings were great big things, like in some Japanese monster movie."

"At first, yes. But a Swarm culture-a Mother-how to say?- evolves in response to stimuli. Its first brute-force attack failed. Now it refines its approach-as I've been warning those fools in Washington it might, all along." His mouth tightened. "I suspect that it is now attempting to emulate the life-form that repulsed it before. Such is a common pattern for these monsters."

"So you've had a lot of experience with these things?"

"Not I. But my people, yes. They are, you might say, our bitterest enemies, these Swarm creatures. And we theirs."

"And now they're, like, infiltrating us?" Mark shuddered. "I think they are a long way from being able to pass undetected. Yet something about this troubles me. Usually at this stage of a Swarm incursion they are not so discriminating."

"And why did they pick on poor Fred?"

"You begin to sound like that horrid woman, my friend." Tach grinned, clapped him on the shoulder. "I hope we'll find the answer to that question when we track these horrors down. Which is the next thing we must do."

"What about Doughboy?"

Tach sighed. "You're right. I will call the police, first thing in the morning, and tell them what we learned."

"They're never gonna buy it."

"I can but try. Get rest, my friend."

They didn't buy it.

"So you found swarmling tissue in Warren's lab," rasped the Homicide South lieutenant in charge of the case. By phone she sounded young, Puerto Rican, harassed, and as if she did not at the moment love Tisianne brant Ts'ara of House Ilkazam. "You are taking a very active interest in this case for a medical expert witness, Doctor."

" I am trying to perform my civic duty. To prevent an innocent man from suffering further. And, incidentally, to alert the proper authorities to a frightful danger which may threaten this entire world."