Even so, the testing focused first on the possible physical causes. Dr. Galen subjected him to cortical analysis, an endorphin response test, three different nondestructive scans of his brain, and even a biopsy and culture for encephalitis.

“Your own awareness of your loss of memory is a clue, as your apparently unimpaired intelligence,” Dr. Galen told Derec. “You retain your sense of time and of the connectedness of events. All of these things are meaningful.”

But the unhappy truth was that all the clues added up to naught, and all the tests revealed nothing. Derec learned several new words to describe his condition-”fractionated retrograde hypnosis-resistant psychogenic amnesia”-but he learned nothing about himself.

“I can find no physical cause,” Dr. Galen concluded reluctantly at the end of a week. “Your cortex, thalamus, mammillary bodies, and fornix bundle are all normal. And yet you have not responded to any psychogenic therapy I am aware of. I am sorry, Derec, I have failed you.”

“Don’t take it so hard,” Derec said, sighing. “I’m beginning to get used to life in the dark.”

In the course of the testing, Dr. Galen had gradually allowed Derec more and more freedom of movement until he had the run of the small hospital complex. Physically, he was nearly completely restored. His new skin was no longer painful to the touch and was gradually becoming less sensitive to variations in temperature. His ribs had knitted while he was kept unconscious, and the only sign they had even been broken was an occasional stitch of dull pain when he drew a deep breath or stretched the wrong way.

Despite that progress, Dr. Galen resisted releasing Derec from his care. The furthest he would go was to allow Derec to move from the ICU to a private room with more traditional accommodations. But the robot’s recalcitrance was not entirely a surprise. With their special First Law responsibility as healers, robot doctors were notorious for their caution.

But Derec suspected that it was not the injuries to his body that concerned Dr. Galen, but the injury to Derec’s mind. The real reason for keeping Derec nearby was to keep him under observation while he treated Katherine. Since Dr. Galen could not be in two places at once, he was keeping his two patients in one place.

Derec could not order Dr. Galen to stop worrying about him, so he resigned himself to living within the robot’s restrictions. In some ways, Derec welcomed the vacation from responsibility. His body had had time to heal, but his mind still vividly remembered the erupting surface of the asteroid, the electric blue pain from Aranimas’s stylus, the sudden flash of the booby trap exploding in his face. He had a right to a few days of peace.

Or so Derec thought. But one day of idleness was enough to satisfy that need. The next morning he did not wait for Dr. Galen’s ritual visit and examination, but went looking for the robot himself. He found him standing at the biomedical monitor at the foot of Katherine’s bed in the ICU.

“Good morning, Derec,” the robot said. “I am sorry that I was delayed. How are you feeling today?”

“Restless,” Derec said. “I’m ready to get back to a normal life.”

“But you are in the fugue state of an amnesiac episode,” Dr. Galen said. “A normal life is not possible for you now.”

“I’ll settle for the substitute at hand,” Derec said. “I can’t just sit around here hoping my memory will come back.”

“What is it you wish to do?”

“I guess I won’t know until I find out what’s already been done for me,” Derec said. “Outside of the robots on the station, who knows that I’m here? Is anybody trying to find out who I am?”

“I cannot say,” Dr. Galen said. “I am certain that the station manager reported your arrival to the district supervisor at Nexon, as I did to the medical supervisor. That information may have been passed to any number of interested parties in the interval since. Why, is there someone you would like to contact?”

Derec pointed across the room at the sleeping Katherine. “Her. How much longer till you bring her out?”

“I concluded some days ago that she might hold the key to unlocking your loss of memory, and decided to allow her to wake at the earliest opportunity when her own health and comfort would not be at risk,” said Dr. Galen. “She was taken off the sleep-inducing drug at midnight. According to her brain waves, she is dreaming now. I expect her to wake sometime this morning.”

Derec glanced around the ward. There was nowhere to sit except the floor.

“There is no need for you to conduct a vigil,” Dr. Galen said as though reading his thoughts.

“I want to be here when she wakes up.”

Dr. Galen nodded understandingly. “I promise, I will call you.”

Derec whiled away one hour, then another, with a bookfilm titled “The Architects of the Machine.” He hoped to find among its profiles of notable designers and engineers a clue as to who the “minimalist” behind the asteroid colony might have been. With all the more tangible evidence lost or destroyed, it was one of the few unexplored leads left to him. Genius of that sort had to have left a trail.

But only three of the biographies were of contemporary designers, and the choices were entirely predictable. The roboticist Fastolfe. March, the Havalean wizard of micromagnetics. The human ecologist Rutan, whose services were so much in demand by the wealthy on a dozen Spacer worlds.

All three had become celebrities, acclaimed by those who knew nothing about what it took to do what they did. But the engineering community had its own celebrities, based on its own standards. Every exclusive group did-those persons who had won the respect and admiration of their peers but were completely unknown outside the circle. Fastolfe ranked here, too, but March was regarded as a toy-maker and Rutan as a joke.

Yes, he needed an insider’s perspective. Someone would know Derec’s mysterious genius-

“Master Derec, if I may interrupt.”

Derec’s head jerked up. It was the medical orderly. Like Dr. Galen, the orderly had fallen victim to the supervisor’s perverse sense of humor. “Yes, Florence.”

“Dr. Galen said that you should come right away.”

Pushing back the viewer, Derec jumped to his feet. “Coming.”

When he reached the ICU, the sterilization lights were already off and Katherine was beginning to stir. She now wore an ankle-to-neck beige gown, etiquette having changed along with Dr. Galen’s changing perception of their relationship. Derec hung back as Dr. Galen bent over Katherine and spoke softly to her.

“Good morning,” he said. “Don’t try to move.”

But she lifted her head a few centimeters all the same and surveyed the room. “Hospital?” she asked hoarsely.

“Yes, Katherine. I am Dr. Galen.”

“On what station?”

“Rockliffe Station.”

She nodded and looked past Dr. Galen to Derec. “Some rescue,” she said.

Despite her hoarseness, there was a laughing note to her voice that Derec did not like. Taking a step closer, he said stiffly, “We’re both alive, aren’t we?”

“Which just goes to show that there’s no justice in the Galaxy,” she answered, closing her eyes. “I thought you’d have been smart enough to disable Aranimas’s security system before you started to poke around in his hidey-hole.”

“Look, I’m sorry it didn’t go more smoothly,” Derec said, coming to the side of the bed. “But we did get away. And there was something we were going to talk about once we did-”

Her eyes fluttered open and searched past Derec for the robot’s face. “Dr. Galen, the headaches are back,” she said. “Would you ask Derec to leave, please? I just don’t think I can deal with company now.”

“How long could it take to tell me my surname, my homeworld-”

But Dr. Galen intervened, gently pushing Derec back toward the door. “I understand your impatience, Derec. But I must consider Katherine’s health, too. Please leave. I will find out what I can. When she is stronger you can talk with her again, if she consents.”