That day, devoting himself almost exclusively to Ryan, Dr. Hobb conducted numerous tests, though he did not put his patient through another myocardial biopsy. He made the reasonable assumption that the lab had properly analyzed the tissue samples that Dr. Gupta submitted.

As a backup procedure, he ordered a recently devised high-tech analysis of Ryan’s blood, looking for the expression of key genes that would confirm abnormal cardiac-muscle function consistent with inherited cardiomyopathy. He found them.

Ryan had no illusions that Dr. Gupta’s diagnosis would be overturned. What he wanted from Dougal Hobb was the hope that came with knowing he was in the care of a brilliant physician who was as committed to the aggressive practice of his specialty as Ryan had been committed to aggressively building Be2Do.

Dr. Hobb prescribed two of the four medications that were part of Ryan’s current drug regimen, dropped two others, and added three.

At seven o’clock in the evening, in his study once more, before sending Ryan back to Newport Coast, the surgeon provided him with a slim medic-alert phone. By pressing only a single button, twice, Ryan would be connected by satellite uplink with an emergency service.

“Keep it on you at all times,” Hobb advised. “Make a habit of charging it on your nightstand every night. But take it out of the charger and with you when you go to the bathroom, in case anything incapacitating should happen to you there.”

He gave Ryan a list of physiological crises-such as the episode of breathing difficulty-in the event of which the medic-alert phone should be used without hesitation.

“And if I’m notified that your waiting is over, that a match has been found for you,” Hobb said, “I’ll contact you through the same medic-alert service. Time is of the essence in these matters. I don’t like to trust to ordinary phones. Unthinkingly, patients turn them off, set them to voice mail. As long as this device is charged, it’s in service. There’s no OFF switch. So keep it charged and keep it with you. The day may come.”

After a two-hour ride in the chartered limousine with Naraka silent and solemn behind the wheel, Ryan returned home.

He had been served a light boxed lunch at Dr. Hobb’s facility, but he’d had no dinner. He searched the refrigerator and put together a meal of sorts.

Lee and Kay Ting were off duty now, and were in their private quarters-doing what, he did not care. He didn’t suspect them of conspiracy any longer.

Or if he did suspect them just a little, he did not worry that they could harm him further. He had taken control of his fate, and no one in his usual circles knew that he had done so.

Although Dr. Hobb might think his new patient eccentric or worse, he had agreed to honor a request not to inform Samar Gupta that Ryan was now under the care of a new cardiologist.

For seven years, Ryan had self-insured because he loathed the insurance-company and government bureaucracies, as well as the endless paperwork, of the health-care system. A $100,000 check, written as a retainer to Dougal Hobb against all future costs, had bought some relaxation of the usual protocols between physicians.

He intended to continue to keep his periodic appointments with Dr. Gupta, though he would not follow any advice given or take any medications provided by that physician.

Although Ryan didn’t suspect Gupta any more than he did Lee and Kay Ting, if Gupta knew of Hobb’s involvement, he would pass the news along to Forry Stafford, and Forry-or his wife, Jane-would tell Sam.

He believed that Forry was a friend. But friendships failed all the time. Brother turned against brother, since the time of Cain and Abel, and even more frequently, more savagely, in this barbarous age.

Although his heart had reached the unshakable conclusion that Samantha was faithful to him and could never betray him, and though his mind was largely in agreement with his heart, he remembered well what she had said so recently at dinner.

If you knew me as completely as I know you, you might not love me.

He loved her as he had never loved another, and he trusted her as he had allowed himself to trust no one else. But by the nature of the world, those who loved and trusted were uniquely vulnerable.

Human beings are such knotted, desperate pieces of work-it’s a rare thing to know one completely, to the core, and still love him.

Perhaps that had been the most honest, the most self-revealing, and the most loving thing that anyone had ever said to him.

But in his present distress, which so easily could spiral into despair, he could not entirely dismiss the possibility that her words might have constituted a consummate act of manipulation.

He didn’t like himself much right now. He might not like himself much for a long time. But he liked himself enough to want to live.

Sitting on a stool at the smaller of the two kitchen islands, preferring to dine by only the light in the cooktop hood, he ate halloumi cheese on zaatar crackers, black olives, slices of soujouk, and cold asparagus. He finished with a fresh pear and a handful of shelled pistachios.

He suspected that in the weeks and months ahead, he would be taking more meals alone than he might wish.

After consulting the labels on each of the five bottles of drugs supplied by Dr. Hobb, he took the medications as prescribed.

Upstairs, in his bedroom, he inserted the medic-alert phone in the charger and stood the charger on his nightstand, so close to his bed that he should be able to reach it regardless of his condition. As he had done the past few nights, he would go to sleep comforted by the light of a lamp. Recently, waking in darkness had felt like coming awake in a sealed casket after being prematurely buried, with too little air to long sustain him.

Lying in bed, with the TV tuned to an old Western-John Wayne in The Searchers-Ryan reviewed the decisions he had made this day, and he felt good about them.

He had tremendous confidence in his new cardiologist, although even Hobb had been stumped by one thing. The doctor had not been able to explain adequately the soft insistent knocking that now and then rose within Ryan, although the physician firmly ruled out the notion that it could be some kind of blood-and-muscle problem related to the cardiomyopathy.

Hobb suggested that the sound instead might indicate a hearing problem, a malady of one ear or the other. Eventually, Ryan pretended to consider that possibility, but remained certain that the rapping had originated not in the nautilus turns of either ear, but within his chest.

Less than half his attention was with John Wayne in the post-Civil War West, because he lay waiting for the rap-rap-rapping to resume.

Eventually, as the movie drew toward an end, as wave after wave of weariness washed Ryan toward needed sleep, he thought that perhaps the knocking would not come again because he had already answered it, had opened the door.

He did not know what he meant by that. It was the kind of muddy thought that eddied through a mind half submerged in sleep’s river.

And so he slept.

During the night, a landscape materialized around him, and for the first time in months, a dream returned him to one of the places that had disturbed his sleep in September.

In the beginning there was only an impression of depth. Waste and void, bottomless and terrifying.

Then the void became water, invisible without light, silent without currents, neither warm nor cold, sensed rather than felt.