"How?" she murmured.

"Boo," the blonde murmured, and Catherine froze.

The investigators passed through the doorway. At the last moment, the ADA turned.

"You ever hear of GSR?" Copley asked.

"No."

"It's gunshot residue. Anytime someone fires a gun, traces of GSR end up on their hands and clothing. Guess what we tested for at the morgue, Mrs. Gagnon? Guess what we didn't find on your husband's hands or clothing?"

Catherine didn't say a word. Boo, she was thinking wildly. Boo.

The trio headed down the front steps.

"One mistake," Copley called back over his shoulder.

"That's all I need. One little mistake, Mrs. Gagnon. Then, you're mine." Monday morning, the sun was shining, the air crisp with the promise of winter. Half of the pedestrians in Boston scurried from overpriced shop to overpriced shop, their heads tucked like turtles deep in the folds of their scarves, their hands crammed into the pockets of their coats. Not Mr. Bosu. He walked through the Public Garden with its grand old trees, no coat, no hat, no gloves. He loved this kind of weather. The scent of the decaying leaves. The last gasp of a fading winter sun.

When he was a kid, this had been his favorite time of year. He'd stay outdoors playing long after dark. His parents didn't care. Being outside was good for the boy, his father would say, before burying himself once more in the daily paper.

Not a bad childhood. He really couldn't complain. He had fond memories of G.I. Joe figurines and toy cement mixers. He rode his dirt bike, played well with the other children. Even had birthday parties in his mother's gold-colored living room, decorated with the little orange and yellow flowers people thought were absolutely darling back then.

He heard it was all coming back in fashion now. Retro. That was the word. Mr. Bosu had been in prison just long enough for his childhood to once again become cool.

He wondered what would happen if he returned home. His parents probably lived in the same house on the same block; hell, maybe they even drove the same car. If it's not broke, don't fix it, the senior Mr. Bosu had always liked to say.

They never visited Mr. Bosu in prison. Not once. After the day that girl had taken the stand, pointed at Mr. Bosu, and said, "Yes, sir, that's the man who grabbed me," his parents hadn't even attended the trial.

He supposed you could say he'd broken his parents' hearts. People like them were supposed to have an ordinary son. One who would join ROTC, end up with a college degree and serve his country on weekends. Then he'd marry an ordinary girl, maybe a younger version of his mother, and she would stand in a vogue retro kitchen, whipping up retro casseroles while their two point two children played with retro toys out back.

Mr. Bosu's fantasies were different. They involved a Catholic schoolgirl in a green plaid skirt and white knee-high socks. She would have her long dark hair tied back in a red bow. She would carry her schoolbooks tight against her just-budding chest. She would say "Yes, sir" or "No, sir." She would have a tight virginal body, untouched by any man, and she would do whatever he wanted, how he wanted, when he wanted. She would be his forever.

Mr. Bosu hadn't been a dumb boy. He'd kept his fantasies to himself. When he was sixteen, he'd made his first attempt. Approached a girl in a playground, pretending to be looking for his younger sister. The girl hadn't run away immediately, so he'd offered to push her on the swing. The feel of her small bony ribs beneath his hands, however, had led to consequences. His pants had been too tight, no way to hide the results. She'd gotten one look, started to scream, and run all the way home.

Later, her parents had approached his parents about his "inappropriate" behavior. He'd blushed, stammered, lied shamelessly that he'd actually been watching a blonde cheerleader walk by. Of course he hadn't meant… He just didn't know how to control… Oh gosh, he was just so, so sorry. Boys will be boys, his father had said, shaking his head and reaching once more for his paper.

After that, he'd been more careful. Taking his parents' car, driving far away from the neighborhood. He practiced and he learned. Nicer clothes were less threatening, particularly given his hulking size. A good story was important. Not candy, everyone warned their children about strangers bearing candy. Better to be looking for a lost sister, lost cat, lost dog. Something a child could relate to.

He learned, he perfected. And one day, he struck.

It was short, messy. Not at all like he'd pictured. Afterwards, he panicked. Didn't know what to do with the body. Finally he'd weighted it down and driven all the way to the Connecticut border, where he found a river.

He'd returned home shaken, disturbed, and interestingly enough, remorseful. He'd watched the news for days, palms sweating, waiting to be discovered.

But nothing happened. Simply… nothing. And then the fantasies started again. He dreamed and he hungered and he wanted. Until one day, he'd turned down a street not far from his parents' house, and there had been the girl. She'd been wearing a brown corduroy skirt instead of green plaid, but otherwise, she'd been close enough.

It had been surprisingly simple after that. He'd approached it a whole new way, and it had been satisfying. Right up until that moment when the girl had taken the witness stand.

He'd been young still. He saw that now. He'd been young and he'd made mistakes. Of course, he'd now had twenty-five years to learn better, and people who didn't think you got an education in prison had obviously never been there.

Mr. Bosu wandered down Park Street until he found the giant Gothic cathedral he remembered from his youth. He sat outside on one of the wooden benches, next to an elderly woman who was feeding bread crumbs to the pigeons. She smiled at him. He warmly smiled back.

"Lovely morning," he said.

"It is, it is," the woman said, and gave a little giggle.

Yesterday, he'd gone on an afternoon shopping hinge, courtesy of Benefactor X. The oversized, slightly menacing man from Faneuil Hall was gone. In his place was a classy, middle-aged gentleman who obviously prided himself on being fit. Oh, the wonders of Armani and a decent haircut.

The old woman threw more crumbs at the fat pigeons waddling around their feet. Mr. Bosu tilted back his head and lifted his face to the sun. Damn, it felt good to be outside.

Presently, the church bells started to ring. Grand wooden doors were thrown open. Families poured down the front steps, first proud fathers, then harried mothers, and then finally screeching children.

Mr. Bosu opened his eyes. He admired dark-haired girls, their long lustrous locks tied back in big white bows. He smiled at the teeming throngs of little blonde princesses, all flouncy white dresses and high-polished Mary Janes. In the vast city block yawning in front of the church, parents were already deep in conversation with other parents while their children ran wild.

Here were five little girls playing tag. Here were two little girls swinging arms. Here was one little girl, already half unnoticed, chasing the scattering pigeons.

"Beautiful, aren't they?" the elderly woman said.

"Nothing so attractive on earth," he assured her.

"Makes me remember my own youth."

"Funny, mine too."

He smiled once more at the woman. She looked a little puzzled, but smiled back. He got off the bench and walked into the sea of young, racing bodies, feeling the breeze of their quick passes like a tingle up his spine.

He walked to the front steps of the church, ascended to the two large doors, then turned and surveyed his kingdom.

People had a tendency to be wary in the city. But this was a particularly upscale area. A posh little island in the middle of an ocean of concrete. Besides, people grew lax in the comforting embrace of their church. They paid more attention to their earnest networking, or the contest over who was driving the right kind of car or drinking the right kind of coffee. They liked to believe they were keeping watch over little Johnnie or little Jenny out of the corner of their eye. But they weren't. Children wandered away, particularly when their parents were talking to other adults. Sometimes, they never wandered back.