“You were away too long,” the Khan mutters. “Enjoying yourself? Yes. But the headache, Shadrach, the miserable hideous headache — I shouldn’t have let you go. Your place is here. Beside me. Watching me. Healing me. It was like sending my right hand on a voyage around the world. You won’t go away again, will you, Shadrach? And you’ll fix my head? It frightens me. The throbbing. Like something trying to escape in there.”

“There’s no reason to worry, sir. We’ll fix you soon enough.”

Genghis Mao rolls his eyes in torment. “How? Chop a hole in my skull? Let the demon escape like a whiff of foul gas?”

“This isn’t the Neolithic,” Shadrach says. “The trephine is obsolete. We have better methods.” He touches the tips of his fingers to the Khan’s cheeks, probing for the sharp, upthrusting bones. “Relax, sir. Let the muscles go slack.” It is late at night, and Shadrach is exhausted, having flown this day from San Francisco to Peking, from Peking to Ulan Bator, having gone at once to Genghis Mao’s bedside without pausing even for fresh clothing. His mind is a muddle of time zones and he is not sure whether he is in Saturday, Sunday, or Friday. But there is a sphere of utter crystalline clarity at the core of his spirit. “Relax,” he croons. “Relax. Let the tension flow out of your neck, out of your shoulders, out of your back. Easy, now, easy—”

Genghis Mao scoffs. “You aren’t going to cure this with massages and soothing talk.”

“But we can ease the symptoms this way. We can palliate, sir.”

“And then?”

“If necessary, there are surgical remedies.”

“You see? You will chop open my skull!”

“We’ll be neat about it, I promise.” Shadrach moves around behind Genghis Mao, so he will not be distracted by the need to maintain eye contact with the fierce old man, and concentrates on diagnostic perceptions. Hydrostatic imbalance, yes; roeningeal congestion, yes; some accumulation of metabolic wastes about the brain, yes. The situation is far from critical — action could be deferred for weeks, perhaps for many months, without great risk — but Shadrach intends to deal swiftly with the problem. And not only for Genghis Mao’s sake.

Genghis Mao says, “It’s good to have you back.”

“Thank you, sir.”

“You should have been here for the funeral. You would have had a front-row seat. It was magnificent, Shadrach. Did you watch the funeral on television?”

“Of course,” Shadrach lies. “In — ah — in Jerusalem. I think I was in Jerusalem then. Yes. Magnificent. Yes.”

“Magnificent,” says Genghis Mao, dwelling lovingly on the word. “It will never be forgotten. One of history’s great spectacles. I was proud of it. The Assyrians couldn’t have done better for old Sardanapalus.” The Khan laughs. “If one can’t attend one’s own funeral, Shadrach, one can at least satisfy the urge by staging a splendid funeral for someone else. Eh? Eh?”

“I wish I could have been there, sir.”

“But you were in Jerusalem. Or was it Istanbul?”

“Jerusalem, I think, sir.” He touches Genghis Mao’s temples, pressing lightly but firmly. The Chairman winces. When Shadrach presses the sides of Genghis Mao’s neck, just below and behind the ears, the Chairman grunts. “Tender there,” Genghis Mao says.

“Yes.”

“How bad is it, really?”

“It’s not good. No immediate danger, but there’s definitely a problem in there.”

“Explain it to me.”

Shadrach moves out where Genghis Mao can see him. “The brain and spinal cord,” he says, “float, literally float, in a liquid we call cerebrospinal fluid, which is manufactured in hollow chambers within the brain known as ventricles. It protects and nourishes the brain and, when it drains into the spaces surrounding the brain, it carries off the metabolic wastes resulting from the brain’s activity. Under certain circumstances the passageways from the ventricles to these meningeal spaces become blocked, and cerebrospinal fluid accumulates in the ventricles.”

“Is that what’s happening to my head?”

“So it seems.”

“Why?”

Shrugging, Shadrach replies, “It’s usually caused by infection or by a tumor at the base of the brain. Occasionally it comes on spontaneously, without observable lesion. A function of aging, maybe.”

“And what are the effects?”

“In children, the skull enlarges as the ventricles swell. That’s the condition known as hydrocephalus, water on the brain. The adult cranium isn’t capable of expansion, of course, so the brain must bear all the pressure. Severe headaches are the first symptom, naturally. Followed by failure of physical coordination, vertigo, facial paralysis, gradual loss of eyesight, periods of coma, general impairments of cerebral functions, epileptic seizures—”

“And death?”

“Death, yes. Eventually.”

“How long from first to last?”

“It depends on the degree of the blockage, the vigor of the patient, and a lot of other factors. Some people live for years with mild or incipient hydrocephalic conditions and aren’t even aware of it. Even acute cases can drag on for years, with long periods of remission. On the other hand, it’s possible to go from first congestion to mortality in a matter of months, and sometimes much more quickly even than that, if something like a medullary edema develops, an intracranial swelling that disrupts the autonomic systems.”

These recitals of symptomatology and prognosis have always fascinated Genghis Mao, and intense interest is evident in his eyes now. But there is something else, a haunted look, a flashing look of dismay verging on terror, that Shadrach has never observed in him before.

The Chairman says, “And in my case?”

“We’ll have to run a full series of tests, of course. But on the basis of what the implants are telling me, I’m inclined toward quick corrective surgery.”

“I’ve never had brain surgery.”

“I know that, sir.”

“I don’t like the whole idea. A kidney or a lung is trivial. I don’t want Warhaftig’s lasers inside my head. I don’t want pieces of my mind cut away.”

“There’s no question of our doing that.”

“What will you do, then?”

“It’s strictly a decompressive therapy. We’ll install valved tubes to shunt the excess fluid directly into the jugular system. The operation is relatively simple and much less risky than an organ transplant.”

Genghis Mao smiles icily. “I’m accustomed to organ transplants, though. I think I like organ transplants. Brain surgery is something new for me.”

Shadrach, as he prepares a sedative for the Chairman, says cheerfully, “Perhaps you’ll come to like brain surgery as well, sir.”

In the morning he seeks out Frank Ficifolia at the main communications nexus deep in the service core of the tower. “I heard you’d returned,” Ficifolia says. “I heard it, but I didn’t believe it. For Christ’s sake, why’d you come back?”

Shadrach eyes the banks of screens and monitors warily. “Is it safe to talk here?”

“Jesus, do you think I’d bug my own office?”

“Someone might have done it without telling you about it.”

“Talk,” Ficifolia says. “It’s safe here.”

“If you say so.”

“I say so. Why didn’t you stay where you were?”

“The Citpols knew where I was, every minute. Avogadro himself dropped in on me in Peking.”

“What did you expect? Taking commercial transport all around the world. There are ways of hiding, but — did Avogadro make you come back here, then?”

“I had already bought my ticket.”

“Jesus, why?”

“I came back because I saw a way of saving myself.”

“The way to save yourself is to go underground.”

“No,” Shadrach says emphatically. “The way to save yourself is to return and continue to carry out my functions as the Chairman’s doctor. You know that the Chairman is ill?”

“Bad headaches, they tell me.”

“Dangerous headaches. We’ll need to operate.”

“Brain surgery?”