“But the planet might have been a lot more active in the distant past,” Solari pointed out. “Even if it wasn’t, the evidence would be buried pretty deep by now. To say that the people on the ground haven’t even begun scratching the surface would be an understatement. But what really matters, I suppose, is whether you’re right or wrong about the world being a death trap now.”

“Unfortunately,” Matthew said, “the answer to that one depends on the answers to all the other questions—including the ones Lityansky didn’t want to address, like the possible relevance of serial chimeras. Maybe the relative dearth of chitin and hard bone isn’tthe product of a blind spot in the protein-coding mechanism. Maybe there’s another factor militating against rigidity.”

“Serial chimeras?,” Solari echoed. “Like werewolves, you mean.”

“Not exactly—but I’ll have to devote some time to figuring out what I mightmean. What have you been doing while I’ve been taking lessons in xenobiology?”

“Checking the list of murder suspects.”

“Really?” The news was sufficiently interesting to make Matthew lift his head a little higher and turn to lie sideways, supporting himself on his elbow.

Solari had obviously been practicing his keyboard skills, because it required no more than a casual sweep of his fingers to replace the single image on the wallscreen with a mosaic consisting of seven faces arranged in two ranks, four on the upper and three on the lower. Matthew took due note of the symbolism of the empty square at the right-hand end of the bottom rank: the blank where a photograph of one of the alien humanoids might be, if the alien humanoids still existed. Even at a relatively oblique angle, Matthew had no difficulty identifying two of the faces.

“The second from the left on the top row’s Ikram Mohammed,” he said. “A first-rate experimental genomicist. Did some remarkable work on intron architecture and functional gene-nesting. I met him a dozen times at conferences. Bernal would have known him fairly well too—whatever Bernal was working on or thinking about, he’d have shared it with Ike. More of an acquaintance than a friend, but I feel confident saying that he’s not a likely murderer.”

“I’ve looked at his CV,” Solari said, noncommittally. “Do you know any of the others?”

“Lynn Gwyer, directly below him. Genetic engineer specializing in agricultural pharmaceutical production. Did a lot of work on bananas. Regarded by some—but certainly not by me—as a plague-war draft dodger, mainly because she dedicated her efforts to attempts to protect Third World innocents rather than First World software engineers. Bernal probably knew her better than I did, maybe better than he knew Ike Mohammed. Again, an acquaintance rather than a friend, but also not a likely murderer, in my opinion. In fact, a highly unlikely murderer.”

“None of them is a likelymurderer,” Solari said, a trifle impatiently. “Few murderers are, alas—especially when it comes to domestics. This has to be reckoned a domestic of sorts. They’d all been living together for months. One big happy—or not-so happy—family.”

“Why not so happy?”

“There’s always friction in living space that small. There were disagreements. Personal as well as theoretical.” He didn’t elaborate, presumably because it was gossip rather than real evidence.

“Who are the others?” Matthew asked.

Solari started at the top left-hand corner, with a man who might have passed for Shen Chin Che’s son in a dim light. “Tang Dinh Quan,” he reported. “Analytical biochemist. Very accomplished, apparently. Two daughters still in SusAn, but no partner—just like you. Reported to be showing signs of strain and acute anxiety in the last few months, becoming increasing vocal in his support for the Base One party advocating withdrawal from the world.”

“Reported by whom?” Matthew inquired.

“The resident doctor, Godert Kriefmann,” Solari said, passing on to the image on the other side of Ikram Mohammed’s face, of a solidly built, square-jawed man whose head had been comprehensively depilated. “He’s a medical researcher too, of course, but the doctors on the surface have had more work to do than they expected. The smartsuits designed for surface use are reasonably strong, and they seem to work very well inside the body, protecting the lungs and the gut from orthodox invasion, but some of the local wildlife is pretty dangerous. Some wormlike things have nasty stings and surprisingly powerful jaws, and some of the mammal-equivalents have tongues like harpoons. To make a smartsuit capable of resisting all the local armaments would inhibit movement considerably. Fortunately, the toxins are more painful than life-threatening, and Kriefmann’s working to develop antisera with Maryanne Hyder, toxicologist.” Solari’s finger dropped to the image beneath Kriefmann’s. It was a study in contrasts: Maryanne Hyder’s face was slender, almost elfin, and she had an abundance of carefully coiffed blond hair.

“She seems to be the one that Bernal was playing happy families with at the time of his death,” Solari reported. “Very cut up by his loss, apparently. Quiet and methodical beforehand, now more hysterical than Tang. On the surface, the least likely of all the suspects—but if it is a domestic, she’s the closest thing we have to a spouse, which might put her under the microscope ahead of all the rest if this weren’t such a bizarre crime. In my experience, domestic murders don’t often involve alien artifacts, real or faked, and they almost always take place inside the home, not in a field two miles away.”

The policeman’s finger moved on to the only remaining woman, whose picture was at the far end of the top row. She was darker than any of the others, and her face was extensively scarred, as if by smallpox or some other supposedly extinct disease.

“Dulcie Gherardesca, anthropologist,” Solari reported. “The most recent arrival at the base, sent to study the ruins of the city in the hope of building a fuller picture of the technological resources and folkways of the humanoids. Spent less time safely enclosed in the bubbles than most of the others, although Hyder and Mohammed both picked up more injuries. Probably better equipped to fake alien artifacts than any of the others, and with more opportunity to do it, but everything else in her background makes her just as unlikely a murderer as the others. A victim of plague war in infancy, very nearly died—said to be fiercely dedicated to her work.”

The last remaining picture showed a blond man wearing a hat and a wide smile. He was carrying a rifle.

“Rand Blackstone,” Solari reported. “Specialist in survival skills. Professional soldier, served with UN forces in half a dozen shooting wars—all spinoff from the plague wars. Argumentative type, but most of his arguments seem to have been with Tang, not Delgado. No doubt at all that he’s capable of killing, but he was there to protect the people at Base Three, and losing one of them is a blot on his reputation. If Milyukov’s right about there being a conspiracy to protect the murderer, it’s difficult to believe that he’d be in on it. Insofar as there’s been an investigation, he’s done it—but he’s no detective. He seems to have made up his mind very quickly that it wasn’t any of the people stationed at the base, and must therefore have been an alien, even though he hasn’t seen the slightest sign of a humanoid since he was commissioned to help set up the operation—he was part of the original group sent over from Base One, along with Mohammed, Gwyer, and Delgado. The others shuttled down a couple of weeks later.”

“Does anyone except Tang have family still in SusAn?” Matthew asked, curiously.

“No, but Kriefmann has a wife, also a doctor, at Base One. Gwyer’s ovaries were stripped and the eggs placed in storage in the gene banks, so I suppose she could be said to have potential children up here—but then, all the males have made sperm donations. Gherardesca’s the odd one out on that score. She was sterilized by a plague-war agent that nearly killed her. Nothing as refined as a chiasmalytic disruptor—an artificial variant of systemic lupus erythromatosus, whatever that is.”