“Dead?” Mark Kaufmann asked. “How could he possibly be dead? The St. John body was in good health. I saw it myself before I went to San Francisco.”

The medic shook his head. “There was a total breakdown of autoimmunity. A civil war inside him, so to speak. No hope whatever of saving him.”

—Murder, Paul’s persona said. But it did not take any great shrewdness to see that. Mark said, “Can such a thing happen naturally?”

“Most unlikely. You realize, Mr. Kaufmann, that it’s statistically possible for such a thing to occur, but—”

“Not very probable?”

“No. Not at all.”

“What was it, then? Carniphage?”

“These are not the effects of a carniphage,” said the medic. “However, the poisoner today has an extremely wide choice of drugs. I’ve been running a data check, comparing effects with possible causes, and this is what I’ve come up with.”

He handed Kaufmann a data sheet. It was headed: CYCLOPHOSPHAMIDE-8 Mark scanned it hastily. “Is this drug easily available?”

“I’d say it costs roughly a million dollars fissionable an ounce,” the medic replied. “The lethal dose is perhaps a hundredth of an ounce, though.”

“Expensive, but not prohibitive. Rare?”

“It can be had. The sources are difficult to reach, but they exist. With enough money—”

“Yes, with enough money,” Mark said. “Have you found any traces of this — this cyclophosphamide in the body?”

“It leaves no traces. It metabolizes completely in use, and the only indication it leaves is in its effect.”

“In other words, proof of use has to be empirical, deduced from the ruin it makes out of the victim?”

“Essentially, yes,” said the medic smoothly. “The quaestorate is now conducting a second autopsy, and naturally will be making every effort to determine the actual cause of death. But I venture to predict that the ultimate verdict will be the same as mine: poisoning by cyclophosphamide-8.”

“All right. Thank you. Go.” — You need to tighten your security net, Paul told him. A murder committed in your own apartment is shameful. “There are finite limits to security,” Mark said. He moved about the apartment, scuffing at the carpet. This incident left him tense and baffled and angry. He did not mind at all that someone had discorporated Martin St. John. the dybbuk Paul Kaufmann, so speedily after the transplant. But it offended him that St. John could be discorporated right here, of all places. And he was troubled by the possibility that suspicion of the discorporation might come to rest on him.

It was poor business. If the quaestorate hatched the idea that he was in any way connected with the murder, he’d be hauled down on a mindpick warrant, and not all the money in the universe could buy him out of that. Naturally, the mindpick would show that he had no complicity in the discorporation of Martin St. John, since in fact he had not been involved at all.

But at the same time the mindpick would reveal the illegal presence in his mind of the persona of Paul Kaufmann.

This had to be the work of Roditis, Mark thought. To take advantage of his absence by sneaking an agent in here to kill St. John, thereby opening him to mindpick and disgrace — no, no, Roditis could have no inkling of what he had been up to in San Francisco, and it was a mistake to attribute to the man more deviousness than he actually possessed — unless, that is, Roditis had his hooks into the lamasery too, and had instantly received word that Mark had come there to undergo a sub rosa persona transplant…

Exhausted by the intricacy of his own hypotheses, Mark sank down on a couch to collect himself.

—Fool, you’re panicking over this. “Let me think, Paul. Please.” — Think all you like. But think fast! An hour from now you may be under arrest.

“No, there’s more time than that. The quaestorate hasn’t finished the autopsy. And then they’ll have to move through channels, deciding if they dare to arrest me, swearing out the warrant, arranging the mindpick. I’ve got at least twenty-four hours.” Paul did not reply. His head aching, Mark attempted to reconstruct the sequence of events. He had seen Donahy Tuesday afternoon. That same day Santoliquido had called to announce his intention of transplanting Paul’s persona into the vacated St. John body. On Wednesday, Mark had inspected the St. John body, then had flown to San Francisco. Also on Wednesday, Donahy had abstracted last year’s persona recording of Paul Kaufmann from the archives. Wednesday night, in San Francisco, Donahy had transplanted the persona into Mark. Mark had remained out there on Thursday, resting and adapting to the powerful new persona. Meanwhile, in New York on Thursday, the most recent Paul Kaufmann persona had been transplanted into the St. John body, and St. John had been taken to Mark’s apartment for recuperation. Sometime late Thursday night St. John had been murdered.

Now it was Friday afternoon, and Mark, back from San Francisco, found himself in deep trouble. Just when everything had been going so well, too. He and Paul had adjusted to one another remarkably smoothly. There had been none of the tests of strength, none of the jockeying and probing that might have been anticipated when strong-willed old uncle entered strong-willed nephew’s mind. Paul had been delighted at getting a new carnate trip, fascinated by the shady way Mark had obtained his persona, and absolutely overjoyed to learn that a second and later version of himself was also going to be at large in dybbuk form. He showed no resentment of the fact that the provision in his will barring transplant to a member of his family had been circumvented, possibly because that codicil had been added after this particular persona had been recorded. Recognizing Roditis as the real family enemy, Paul was willing to aid his nephew in every way, while at the same time helping to isolate and immobilize the dybbuk-Paul whom Santoliquido had spawned. Of course, Mark was prepared for conflict with his uncle sooner or later, possibly even a sneaky attempt to go dybbuk at his expense. But for now, at least, their mutual adaptation was splendid, and Mark reveled at having the crusty, indomitable old brigand finally safe in his mind.

Then, to fly home and walk into this — Well, there were certain obvious first steps to take. The most obvious of all was to check last night’s scanner records and see who had been in his apartment. He had a pretty good idea. There weren’t many people who had even conditional access, and the only one with full access, Risa, was still in Europe, so far as he knew.

The scanner file gave him the quick answer. Elena had been here. She had applied for admission just before eleven last night, and the robots had let her in. Mark saw her on the tape, and there was nothing unusual about her expression, as there might have been if she had come to commit a discorporation.

But who was this who had come in with her? This tall, blond fellow with the taut, edgy look in his eyes?

Noyes? Charles Noyes? Noyes of Roditis Securities?

Elena had brought him here?

—There’s your killer, Paul said. He must be. “Not so fast,” Mark muttered. “Noyes is Roditis’ man, sure, but Roditis doesn’t do foolish things. If he wanted to kill St. John, he wouldn’t send someone like Noyes here to do the job. It’s too transparent.”

—What do you know about Noyes? I recall that he’s not too stable.

“No, not very.” — Then perhaps Roditis picked a bungler. Run the tape a little further.

Mark moved it along. The figures of Elena and Noyes appeared at the door again some ten minutes later. Noyes looked more tense than ever, almost close to collapse. And Elena, now, gave every impression of hysteria. Obviously something significant had happened in those ten minutes — such as the murder of Martin St. John. The two figures were exchanging hurried conversation at the door. Mark could not read their lips, nor was there any audio on the scanner tape, but he knew that a simple computer analysis of lip patterns would tell him what they were saying. He watched Noyes hurry from the apartment. Then Elena disappeared from the door. About twenty minutes later she left looking calmer. That concluded the Thursday night record. The file of outgoing calls showed none until one in the morning, when a robot had noticed St. John dead and had summoned the quaestors.