Professor Rosenthal adjusted the flow of water from the handheld sprayer, carefully rinsing the thick white suds through her patient's long, dark hair. The man reclined in the salon chair with his eyes closed, a towel protecting his shoulders and a dusty-rose cape covering the rest of him. He looked remarkably peaceful for someone who, only an hour earlier, had been pacing the laboratory and demanding to know why he had been brought there.

Tatiana stood beside the trolley of bottles and instruments, watching her mentor work. She wore a neat powder-blue blouse and a charcoal skirt, her blonde curls arranged meticulously around her face. Although she had been Professor Rosenthal's apprentice for only a few weeks, she had already witnessed enough of the professor's extraordinary work to understand that conventional science had little to say about what happened in this room.

"Will he remember any of this?" Tatiana asked, glancing at the unconscious-looking man.

Professor Rosenthal smiled faintly. "No. She won't even remember she was a man."

Tatiana looked at the patient again. The subject's strong jaw and heavy brows were still unmistakably masculine, despite the shampoo working its way through his hair. She had been told his history before the procedure began. He had been a brutal man, someone who had used his size and strength to intimidate others, who had treated kindness as weakness and other people's suffering as an inconvenience. The professor had spent weeks studying his memories, personality, and habits before deciding precisely what sort of person should emerge from the treatment.

"The suds are doing more than cleansing her hair," Professor Rosenthal continued, noticing Tatiana's curiosity. "The solution is carrying the old memories away, piece by piece. His childhood, his name, his relationships, his ambitions, even his understanding of his own body. Everything that made him the man he was is being dissolved."

"And the new memories?"

"Being written in their place."

The professor moved the sprayer aside and worked a fresh layer of the pearly foam through the subject's hair. Under the laboratory's specialized lighting, tiny silver flecks shimmered in the suds.

"She'll remember growing up as a girl," Rosenthal explained. "She'll remember being a shy child who hated drawing attention to herself. She'll recall a loving mother, a quiet home, and teachers who encouraged her gentle nature. She'll remember being uncomfortable when people argued and being the first to apologize when she thought she'd upset someone."

Tatiana considered this. "And she'll believe those things really happened?"

"Of course. There will be no gaps for her to investigate, no contradictory memories to trouble her. Her entire personal history will make sense to her. She'll have photographs in her mind that never existed, recollections of conversations that never took place, and the familiar feeling of having lived a life that was carefully constructed for her."

Professor Rosenthal paused to check the instruments beside the basin.

"When she wakes, she'll be a shy, kindly young lady. She'll have no recollection of the cruelty she once inflicted on others. She won't know she ever possessed a man's body, and the thought of having been anyone other than herself will strike her as absurd."

Tatiana glanced at the subject's face. "It's difficult to imagine."

"That's because you're imagining the transition from the outside. She won't experience a transition at all. As far as she's concerned, there will simply be her life, exactly as it has always been."

The professor turned off the sprayer and wrapped a clean towel around the subject's hair. The first stage was complete.

"Now," she said, "let me show you something important."

She gestured toward a framed photograph on a nearby shelf. It showed Professor Rosenthal standing beside Tatiana at a laboratory reception. Tatiana was smiling brightly, her blonde hair curled neatly, her powder-blue blouse fastened to the collar and a small silver brooch pinned beneath it.

"Do you remember when you first came to work for me?" the professor asked.

"Naturally," Tatiana replied. "You interviewed me in your office. I was nervous, but you made me feel welcome."

"And before that?"

"I completed my studies, worked as a research assistant, and applied for the position here."

"Nothing unusual?"

Tatiana frowned. "What do you mean?"

Professor Rosenthal studied her apprentice for a moment. "Three months ago, you were not Tatiana. You were a man named William."