The van turned into a lane of long-dead chestnut trees, and Felder followed. Through the trees, he could see the East River and the numberless silhouetted buildings of Manhattan’s East Side. So near, and yet so very, very far.

The van slowed, then stopped outside a tall wrought-iron gate. A guard stepped out of the security booth beside it and walked up to the driver. He glanced at a clipboard the driver handed him, then nodded, returned to his booth, and opened the gate with the press of a button. As the two vehicles entered the compound, Felder glanced at a bronze plaque on the gate: MOUNT MERCY HOSPITAL FOR THE CRIMINALLY INSANE. There had been some effort recently to change the name to something more modern, less stigmatizing, but the massive plaque looked like it was there to stay.

The van pulled into a small, cobbled parking area, and Felder stopped his Volvo beside it. He got out and stared up at the vast gothic pile, its grand old windows now covered by bars. It had to be the most picturesque — not to mention unusual — asylum in all America. It had taken him a great deal of time and paperwork to arrange for the transfer, and he was not a little irritated that the man who had promised to “reveal all” about the prisoner in return for this favor seemed to have disappeared from the face of the earth.

His gaze quickly shifted from the building to the police van. A prison guard had gotten out of the passenger seat and walked to the rear doors, unlocking them with a key on a large key ring. A moment later, the doors opened and a police officer, uniformed and armed with a shotgun, stepped out. While he waited, gun at the ready, the prison guard reached into the van to help out the other occupant.

As Felder watched, a young woman in her early twenties stepped out into the evening air. She had dark hair, cut in a short, stylish bob, and her voice — when she thanked the orderly for his assistance — was low and even, its cadence reserved and antique. She was dressed in a prison uniform, and her wrists were handcuffed before her, but as she was led toward the entrance her head was held high, and she walked with grace and dignity, her carriage erect.

Felder joined the little group as they walked by.

“Dr. Felder,” she said, nodding gravely at him. “A pleasure to see you again.”

“Likewise, Constance,” he replied.

As they approached the front door, it was unlocked from within and opened by a fastidious-looking man wearing a white medical jacket over an expensive suit. “Good evening, Miss Greene,” he said in a calm, quiet voice, as if speaking to a child. “We’ve been expecting you.”

Constance gave a faint curtsy.

“I’m Dr. Ostrom, and I’ll be your attending physician here at Mount Mercy.”

The young woman inclined her head. “A pleasure to make your acquaintance, Doctor. Please call me Constance.”

They stepped into the waiting area. The air was warm and smelled faintly of disinfectant. “I know your, ah, guardian, Aloysius Pendergast,” Dr. Ostrom went on. “I’m very sorry we couldn’t have brought you here sooner, but it took longer than expected to get the necessary paperwork cleared.”

As Ostrom said this, his gaze briefly met Felder’s. Felder knew that the room Constance was assigned at Mount Mercy had — after a thorough search — been very carefully cleaned, first with bleach, then antiseptic, and then repainted with three coats of oil-based paint. These measures were deemed necessary because the room’s prior occupant had been notorious in her fondness for poisons.

“I’m most grateful for your attentions, Doctor,” Constance said primly.

There was a brief wait while Dr. Ostrom signed the forms handed him by the prison guard. “You can remove the handcuffs now,” Ostrom said as he returned the clipboard.

The guard complied. An orderly let the guard and police officer out and locked the front door carefully behind them. “Very good,” Ostrom said, rubbing his hands together lightly as if pleased by the transaction. “Now Dr. Felder and I will show you to your room. I think you’ll find it quite nice.”

“I have no doubt that I will, Dr. Ostrom,” Constance replied. “You’re very kind.”

They made their way down a long, echoing corridor, Dr. Ostrom explaining the rules at Mount Mercy and expressing hope that Constance would find herself comfortable with them. Felder shot a private glance at Constance. Anyone would find her an unusual woman, of course: the old-fashioned diction, the unreadable eyes that seemed somehow older than the face they were set in. And yet there was nothing about her looks or her manner that could prepare one for the truth: that Constance Greene was deeply insane. Her presentation was unique in Felder’s experience. She claimed to have been born in the 1870s, to a family long gone and forgotten, save for scattered traces in public records. Most recently, she had returned by ship from England. During the voyage, she had — by her own admission — thrown her infant son overboard because, she’d insisted, he was the embodiment of evil.

In the two months since he’d become involved with her case, Felder had — first at Bellevue, then at the Bedford Hills Correctional Facility — continued his analysis of Constance. And while his fascination with the case had only sharpened, he had to admit that he’d made no progress at understanding either her or her illness.

They waited while an orderly unlocked a heavy metal door, then they turned down another echoing passage, at last stopping before an unmarked door. The orderly unlocked this in turn, and Dr. Ostrom ushered them into a small room, windowless and sparsely furnished. All the furniture — bed, table, single chair — was bolted securely to the floor. A bookcase was fixed to one wall, containing half a dozen volumes. A small plastic flowerpot with daffodils from the hospital’s garden sat on the table.

“Well?” Ostrom asked. “What do you think, Constance?”

The young woman looked around, taking in everything. “Perfectly satisfactory, thank you.”

“I’m pleased to hear that. Dr. Felder and I will give you some time to settle in. I’ll send a matron by with more appropriate attire.”

“I’m much obliged to you.” Constance’s gaze settled on the bookcase. “My goodness. Cotton Mather’s Magnalia Christi Americana. Benjamin Franklin’s Autobiography. Richardson’s Clarissa. Aren’t these Great-Aunt Cornelia’s books?”

Dr. Ostrom nodded. “New copies of them. This used to be her room, you see, and your guardian asked us to purchase the books for you.”

“Ah.” For a moment, Constance flushed with what appeared to be pleasure. “It’s almost like coming home.” She turned to Felder. “So nice to carry on the family tradition here.”

Despite the warmth of the room, Felder felt a cold thrill of dismay course down his spine.

LIEUTENANT VINCENT D’AGOSTA STARED DOWN at his desk, trying not to feel depressed. Ever since he’d come off sick leave, his boss, Captain Singleton, had placed him on modified duty. All he seemed to do was push paper from one side of the desk to the other. He glanced out the door into the squad room. There, people were busily coming and going; phones were ringing; criminals were being processed. Stuff was happening. He sighed, glanced back down at the desk. D’Agosta hated paperwork. But the fact was, Singleton had done it for his own good. After all, just half a year ago he’d been lying in a hospital bed in Baton Rouge, fighting for his life, a bullet having nicked his heart. He was lucky to be alive at all, let alone vertical and back at work. Anyway, desk duty wouldn’t last forever. He just had to fully recover his old strength.

Besides, he told himself, he should be looking on the bright side. His relationship with Laura Hayward had never been better. Almost losing him had changed her somehow, softened her, made her more affectionate and demonstrative. In fact, once he was back to one hundred percent he was seriously thinking of proposing. He didn’t think the average relationship counselor would recommend getting shot in the chest, but it had sure worked for him…