He showered—she had installed her own equipment, even arranged a projection of the crystal cavern inside the stall—and dressed. She kissed him goodbye, and before he had fully registered their conversation he was making his way to the suit-up room, shaky but ready for duty.

He was already at work before the hangover cleared and he felt the sudden weight of depression descend again. Ever since leaving Earth, he had worked with single-minded determination, never questioning. But now he couldn’t keep his mind oft bigger issues, problems he could see coming in the days ahead. There was nobody tie could trust to take care of that, not any longer.

Carl felt a yawning emptiness, a foreboding.

Captain Cruz is gone. It just doesn’t seem possible. What in the frozen hell are we going to do?

It should not have been possible.

Saul stared at the patch of green and brown in the petri dish. It didn’t take a lab regimen to know he was looking at something that just shouldn’t exist.

Standing in a relaxed, low-G crouch, Spacer Tech Jim Vidor peered over Saul’s shoulder. Strictly speaking, the man wasn’t even supposed to be here. The decon mask over his mouth and nose were sops to the official quarantine Saul was under.

Saul took a fresh handkerchief from the sterilizer and wiped his nose. After two days, when it seemed his body was in no great hurry to flop over and die from this tsuris of a cold, the isolation order had lost some of its original urgency. To spacers, disease was an abstract threat, anyway. Far more real to them was the trouble they were having with gunk getting into everything from air circulators to mechs, threatening the machinery that kept them all alive.

Nevertheless, Saul motioned for Vidor to stand back—for the same reason he had kept Virginia away, in spite of her mutinous entreaties.

Nick Malenkov might be right, after all. Anything could happen, when Halley was able to come up with things like this on the dish before him.

“The stuff was growing in the main dehumidifier, way up where Shaft One intersects A Level, Dr. Lintz. I showed it to Dr. Malenkov when I got back down here to Complex, but he’s busy full time in sick bay now that Peltier’s keeled over. He said you were the grand keeper of native animals on this iceberg, anyway, so I brought it to you.”

No doubt Nick assumed you’d use a mech messenger, Saul thought. Every few hours a mechanical knocked on his door, carrying a thermos of soup and a tiny note from Virginia. Maybe those little packets were the real reason his dammed bug hadn’t gotten any worse.

Working with his gloved hands in an isolation box, he used sterilized forceps to tease apart a clump of red and green threads, lifting a few onto a microscope slide. The unit whirred as probes crept forward into position. This thing that couldn’t exist obviously did exist. It had to be examined.

Naturally, Malenkov would not be interested in looking at anything as macroscopic as this. As Shift-1 physician, Nick’s chief concern was the strange and terrifying illness that had appeared out of nowhere, killed their leader, and now had another victim prostrate in sick bay.

The “thawing” of Bethany Oakes and half-a-dozen more replacements had been delayed by discovery of brown slime in the warming bins, which had to be cleaned laboriously by hand. The resumed unslotting was now keeping the Russian medic too occupied to bother with anything so large—and therefore “harmless” —as threads blowing in a faraway tunnel.

Saul, exiled to his own lab, had little to do except analyze the tissue samples taken from poor Miguel Cruz and the new patient… and deal with queries from a worried Earth Control. Mostly, he had a broad-spectrum incubation program under way, from which he couldn’t expect results for at least another thirty-six hours.

“Have th’ tests told you anything at all about what killed th’ captain, Doc?”

Saul shrugged. “I’ve found signs of infection, all right, and foreign protein factors, out little more definite than that.” He had come to realize, at last, that he would probably never track down the pathogen, or pathogens, without a lot more data. He needed to know more in a basic sense about Halley lifeforms.

If Nick wouldn’t let him near the patients, then he should be looking elsewhere! What Saul wanted most was to get out into the halls and see for himself… to collect samples, build a data base, and find out what had killed his friend. But this damned quarantine…

He turned his head and lifted a tissue before sneezing. His ears rang and his vision swam for a moment.

Well, at least Jim Vidor didn’t seem to feel in much danger, visiting a presumed Typhoid Mary. He had backed away at the sudden eruption, but as soon as Saul’s composure returned, the spacer stepped back up to look over his shoulder.

“Got any idea what it is, Dr. Lintz? This new stuff was clustered all around the inlet pipes on B level, and I’m afraid it may turn into as big a problem as that green gunk, if it plugs up the dehumidifier.”

Nick and I are scared by the tiny things… microscopic lifeforms that kill from within. But spacers have other concerns. They worry about machines that get clogged, about valves that refuse to close or open, about air and heat and the sucking closeness of hard vacuum.

“I don’t know, Jim. But I think…”

The screen whirled and a tiny cluster of threads leaped into magnified view. Saul cleared his throat and mumbled a quick chain of key-word commands. Abruptly, a sharp beam of light lanced forth, evaporating a tiny, reddish segment into a brilliant burst of flame. One of the side displays rippled with spectra.

“Nope. I guess it can’t be a mutated form of something we brought with us, after all. It has to be native.” Saul rubbed his jaw as he read an isomer-distribution profile. “Nothing born of Mother Earth ever used a sugar complex like that.” He wondered if it even had a name in the archives of chemistry.

Vidor nodded, as if he had expected it all along. Innocence, sometimes, leaps to correct conclusions when knowledge makes one resist with all one’s might.

Saul, too, had suspected, on seeing the stuff for the first time. For it looked like nothing Earthly he had ever seen. But he had found it hard to really believe until now. Microorganisms were one thing he could rationalize that, particularly after seeing JonVon’s wonderful simulation of how cometary evolution could occur. Primitive prokaryotic microbes, yes. But how, in God’s perplexing universe, did there ever get to be something so complex… so very much like a lichen, deep under a primordial ball of ice?

I never really believed Carl Osborn’s story of macro-organisms out in the halls, he confessed to himself. I guess I just pushed it out of my mind, denigrating whatever he had to report, answering hostility with hostility. Instead I kept busy doing routine stuff, studying microbes, ignoring the evidence that something far larger was going on here.

Of course, Carl had not exactly cooperated, either. They had not seen each other since that fateful morning in the sleep slots. And Carl had never sent the samples Saul had asked for. Small wonder he had been so glad when Jim Vidor took the initiative.

“For want of a better word, Jim, I’d have to call this thing a lichenoid… something like an Earthy lichen. That means it’s an association creature, a combination of something autotrophic—or photosynthesizing—like algae, with some complex heterotroph like a fungus. I’ll admit it’s got me stumped. Though. Nothing this complicated ought to—”

“Do you know of any way to kill it?” Vidor blurted. His eyes darted quickly to the screen, where the fibers slowly moved under intense magnification.

Suddenly Saul understood.