"Well, that I can still experience this—I could kiss you!" Lucas Godeau was visibly agitated. He had hardly been able to wait for Elizabeth and her companions to arrive. Godeau, a native of Boston whose ancestors came from France, worked for the BPD in the ballistics department.

The likable, lively Godeau was considered one of the most capable specialists in ballistics. Due to the priority with which Jack's series of murders was treated, he immediately took on the bullet casing. Meanwhile, the bullet from the body of the dead man had reached him from the morgue. The little man with the protruding gap between his upper incisors seemed almost ecstatic about the bullet.

"Whoever fired that bullet must have cherished it for a hell of a long time," he began to report.

Although Elizabeth was more than eager to hear what her colleague had to say, she couldn't help but notice that Nikki and Katherine had been whispering to each other behind her back for some time. "If the ladies can have their private conversations after hours, please," she called them to order. "So, Godeau," she turned back to the ballistics expert, "what have you got for us?"

"The bullet was fired at close range, but it didn't come out, did it? When something unusual happens, the ballistics expert first thinks of a special design. There are many of them in the weapons sector, for example, and that was my first thought: silencer ammunition. Watch this." Godeau placed the projectile, which he had been holding like a diamond since his guests arrived, in a bowl and went to his gun cabinet. He reached for a pistol, made sure it wasn't loaded, and then opened a drawer, from which he took a silencer. "A gun goes off twice when it's fired," he began to explain as he illustrated his execution with the gun in his hand. "The first time is when the bolt hits the cartridge, and the powder charge explodes. That's the bang of the bullet. The second time is when the bullet shoots out of the barrel at supersonic speed. The muzzle blast. If you put a silencer on the gun, you reduce the muzzle blast, not the bullet sound. The shot is then only a few decibels quieter."

Katherine, who, unlike the two investigators, knew next to nothing about firearm peculiarities, listened attentively while Elizabeth and Nikki waited impatiently for Godeau's explanation's punch line.

"That's why almost all secret services have developed special ammunition for silencers. The propellant charge, i.e., the black powder in the cartridge, is reduced in such bullets. The bullet not only makes less of a bang, but it also flies through the air less quickly. It also does not break the sound barrier when it exits. With such a cartridge, the shot is actually dampened quite well. That is why the bullet did not penetrate the victim's body: it was propelled with so little black powder that it simply got stuck. In cases like this, we talk about proximity munitions."

Elizabeth was a little annoyed. She really should have figured it out herself, as there was no plausible explanation for the phenomenon. However, she consoled herself with the fact that she had never fired a pistol with a silencer in her life. Besides, weaponry's intricacies differed from her area of expertise, but that of the ballistics experts. "How long do you think he looked after the cartridge?" Elizabeth returned to Godeau's previous comment.

The ballistician put the pistol and silencer down on a table, pulled out a handkerchief, dabbed his forehead, and then picked up the bullet again. "If I'm not mistaken - more than sixty-five years!"

While Elizabeth and Nikki were visibly surprised, Katherine had a spontaneous idea. "War munitions?" she asked, jotting something down in her notebook.

Godeau nodded slowly. "Everything points to that. The imprints of the rifling and fields on the projectile also tell me the weapon from which the bullet was fired: a Walther P38."

"But the Walther P38 was built long after World War II," interjected Nikki, a very experienced markswoman with a keen interest in weapons.

Godeau pointed at the young woman and frowned a little. "I agree, but now the color of the casing comes into play," he responded to Nikki's objection with a mischievous smile.

Before the investigators arrived, the ballistics expert reached for a book lying on a board and presented his guests with a picture of a cartridge with a casing. "During World War II, agents, especially the Waffen SS, used this special ammunition for missions. To make them recognizable, these cartridges were made with green cases. If you now look at this rare cartridge in connection with the weapon, we are most likely dealing with historical ammunition from a Waffen-SS gun."

"No chance of error?" Nikki asked with a frown.

Godeau pulled down the corners of his mouth and raised his shoulders. "Not ruled out. But I'd be willing to bet my daughter's education on it!"

Elizabeth had already taken in all the relevant details of the room when she entered the lab. She had caught the recent Christmas photo of Lucas Godeau with his wife and a toddler in his arms, wearing blue clothes and a little cap. She was just about to reproach her colleague for not having a daughter when Katherine joined the conversation.

"That's a nice addition to my perpetrator profile."

"So you're saying Jack is a former member of an elite Nazi troop?" Elizabeth objected. "And now, with over a hundred years under his belt, he suddenly decides to get back on top form and cut a bloody swathe through Boston? In a duel against young, strong victims? And all this in the dead of winter?"

"The things that make serial killers what they are develop very early in their lives, almost always during their youth," Katherine replied, crossing her arms in front of her chest. "Children who are exposed to hardship and arbitrariness can develop enormous hatred. Towards others, but above all, towards themselves. Nationalism and self-hatred go hand in hand, and if Jack has a family background, that could explain a lot."

Nobody said anything momentarily before Nikki finally said what everyone was thinking: "Great. If there's anything we can't use, it's a Nazi killer the FBI doesn't know about. Maura will be really excited. And the media --"

xxx

Nick would have loved to throw the list of names out the window. Hundreds of viewers watched every single live show on Your Catwalk. Matching their names was as mindless as it was frustrating. What's more, no name had ever appeared more than once. "Have you ever thought about the production company team?" Nick was suddenly torn from his thoughts.

Daniela Castella had entered the bullpen unnoticed and watched him silently for a few seconds as he sat in front of the pile of documents, absorbed in his work.

"I've already thought of everyone. But the show will probably have a much smaller audience without Tanja Henderson. And that also means less money for the production company."

Castella felt a little sorry for Nick. The investigation meant a lot to him, if only because it was the first time he could prove himself without his sister-in-law and colleague Elizabeth Rizzoli. It must have been difficult to admit to his increasingly likely failure. "What if it wasn't a kidnapping at all but a murder?" The captain pondered aloud with a frown. "Bodies disappear every day."

"Yes, but the question remains: who benefits most from her disappearance? Her siblings would only get their hands on the fortune if she died. As long as she has disappeared, they have nothing. And because there is no inheritance to distribute without a corpse, all other possible heirs are also ruled out. She was never alone in public, and her villa was secured with more surveillance cameras than the senator's house. There are no signs of struggle in the house or evidence that furniture or carpets have been removed or replaced. Classic murder motives are also ruled out. There are no black marks in her past that could justify revenge. Except perhaps for her statements in the casting show, which were often quite harsh and below the belt. But should I now interrogate everyone in this country who was upset by Tanja's nasty remarks?" Nick licked his lips and shook his head in despair. "I'm at my wit's end."

"Maybe another person is benefiting from her disappearance after all." Castella pushed aside the piles of names and sat down on the edge of Nick's desk. "Tanja Henderson herself!"

"You mean she wants to increase her market value by hiding out for a few days to show everyone how indispensable she is?"

Castella smiled and looked at Nick almost amicably. "You know, sometimes we women just want to be alone. It's conceivable that Tanja has given herself a little break. Away from all the hustle and bustle, commitments, contracts, agencies, and paparazzi. I once disappeared for a whole week during my studies without a trace."

Nick furrowed his eyebrows and leaned back in his chair. "You serious?"

Castella pulled the corners of her mouth down. "I was so fed up with it all back then! I was fed up with all this stress; you wouldn't believe it." Her eyes fell on the pile again. "Why don't you consider the possibility that Henderson kidnapped herself just to get away for a few days?"

Nick didn't know what to make of the suggestion. "If I just sit here and wait for the problem to sort itself out, Maura Isles will hang me in her office as a deterrent."

Castella couldn't disagree. "You've got a point," she agreed with her detective. "Between you and me, sometimes when she's pissed off, I wouldn't put it past her to eat someone!" For the first time in hours, Nick smiled. "So, why don't you go back to Tanja's relatives? Little girls all have a hiding place they go to when they don't want to be found. Find Tanja's."

Nick stretched, exhausted, and then leaned back in his chair again. "Why not?" he agreed. "At least I'll get out of here."

xxx

"A lot of people think of serial killers as bloodthirsty beasts who slit the throats of anyone who gets in their way."

Elizabeth had retreated with Katherine to the BPD conference room. Nikki had not joined them. Elizabeth had asked her to go to the morgue instead and find out about possible DNA traces after the fight between Kai Sawyer and his killer.

Elizabeth picked up a glass and the carafe of water in the center of the conference table and looked at her sister with a questioning look. "How many more have you met since your time at Quantico?"

Katherine took a deep breath. "I've had personal conversations with twelve since I started working solely for the FBI. I've studied the files and life stories of over thirty more in detail," the psychiatrist replied, reaching for the water. "We, you and I, have had to deal with a few serial killers. Unfortunately, most of them chose death over science."

"Be fair. Not everyone we've hunted has died," Elizabeth replied with a furrowed brow. "Three just slipped through our fingers. Which serial killer caught by the FBI was your most interesting subject of study?"

Katherine blinked a few times and pressed her lips together. "Alexander Albert Groza, the Butcher of Tallahassee. He murdered homeless people and cut up their bodies the way a butcher does with sides of pork. He was very professional; he could have been something. Unfortunately, he assumes that the wardens of his asylum are aliens who speak to him at night via their hair roots. That's one of the completely crazy ones."

The lieutenant drew in her chin. "Aren't they all?"

Katherine licked her lips and poured herself a glass of water, then reached into her shoulder bag to pull out a book. She placed it on the table, the cover facing her sister. "They're sociopaths, but that doesn't mean they walk around all day with crazy delusions, Liz. Most of them don't really show it at all. In such cases, the neighbors like to talk afterward about how the murderer always greeted them nicely in the hallway or garden."

Elizabeth reached for the book. It was entitled In the Killer's Head, and a picture of Katherine was on the cover. The lieutenant liked the picture. Even if she kept it to herself for the time being. While Katherine continued, Elizabeth flipped through the pages on the side.

"Anyway, serial killers never kill indiscriminately. In fact, they often only commit a single murder - but they do it again and again. In such cases, the victims symbolize a certain type of person. They are often basically relationship crimes that the perpetrator would like to commit but cannot. Let's say he would actually like to kill his hated mother. But either the mother is no longer alive, or the son would simply not be able to kill her for other reasons. In such cases, it sometimes happens that men murder women who remind them of their mother."

"But that also means that this murderer would never think of murdering her letter carrier," Elizabeth continued, her eyes darting over the acknowledgments at the end of the book.

"Unless the letter carrier resembles his mother!"

"For once, I'd be happy if we weren't necessarily dealing with a serial killer. A conventional murder would be enough for me."

Katherine briefly considered how she should react. Finally, she replied, "Is that why my presence pisses you off? Because your captain put me alongside you on your serial killer hunt? Are you afraid of sharing the credit with someone from the FBI?"

Elizabeth snorted in annoyance and stood up from her chair. "I suppose I can assume you're planning to take the credit for yourself anyway. At the end of the acknowledgments, you promise another book. You want to write about Jack when this is over, right?"

Katherine licked her lips once more and took a deep breath. "To be honest, yes. The case excites me, and I haven't dealt with a single serial killer in any of my books."

"You're enjoying it. You get a kick out of it."

Katherine felt the ice between her and her sister slowly melting. "You know what people always say about shrinks: they're all crazy themselves. Well, there must be something to it." When she noticed Elizabeth's skeptical look, she added confidently, "Be happy: motivated employees are the best!"

"Unlike over-motivated ones," Elizabeth replied and sat down again. "Why do you assume that your presence makes me sick?"

"I felt I had interpreted subtle signs."

"As subtle as your whispering with Nikki?"

Katherine couldn't help but smirk. "Nikki has only spoken highly of you!"

"You were talking about my clothes and the fact that Maggie and I broke up," Elizabeth noted with furrowed brows. "Your eyes went to my blouse simultaneously, then to my coat after Nikki took her eyes off me and whispered something in your ear that made you raise your eyebrows in surprise."

Katherine swallowed hard and nodded, intrigued. "How do you know that?"

The lieutenant felt her wedding ring and frowned deeply. "The chances of Nikki whispering a welcome back to Boston to you are vanishingly small, wouldn't you say?"

Katherine noticed an undertone of a friendly approach to the question. However, she decided to ignore it for the time being. She resolutely put down her glass and demonstratively changed her tone when she returned to Jack. "Let's start with the Nazi gun. Almost every serial killer is the product of serious mistakes in their upbringing, so the often ridiculed but almost always true cliché of the difficult childhood. So, if Jack comes from a family that was loyal to the system in the Third Reich and even had SS connections, then it seems pretty certain to me that he grew up in the wake of an ideology in which it was more important to obey than to ask for any reasons. Jack has no tolerance; he knows no liberality. I assume he was brought up by his father."

Elizabeth followed the explanations attentively and without asking any questions.

Katherine took another sip of water and breathed deeply. "He was taught to follow orders. He was probably punished severely for breaking the rules. That's a typical male parenting pattern—men like to make their children conform to themselves and their own thinking, while women tend to give in. His set of values leaves no room for deviation, and now, as an adult, his intolerance has increased to such an extent that he has decided to impose his set of values on others, to assimilate them."

Elizabeth's dismissive attitude towards her sister visibly faded. She beamed satisfactorily and replied, "He could be on record for the relevant offenses. Maybe a troublemaker who constantly reports his neighbors or someone who beats his neighbors' children or shoots at them with a BB gun."

"That sounds right. By the way, Jack is a Bostonian, at least for a long time. Have you noticed how well he chooses his crime scenes?"

"No, I've been too busy looking for curtains for my new apartment."

Katherine rolled her eyes at Elizabeth's sarcasm. "I don't mean that the crime scenes were secluded and deliberate. I mean that they indicate an excellent knowledge of this big city. He seems to consider every out-of-the-way place for his murders, which necessarily means he knows every out-of-the-way place in Boston."

"Your conclusion?"

"I assume he is or was a cab driver. No profession knows a city better. But this profession doesn't fit his perpetrator profile, so he probably drove a cab out of necessity. I assume during his studies."

"What did he study?" Elizabeth challenged Katherine further, smiling meaningfully at her.

"Something that involves non-negotiable rules. Mathematics, physics, maybe law. Nothing creative; there are different views and interpretations. Jack doesn't like to argue. He almost certainly has a job in which he teaches people. Lecturing is his obsession, so to speak. He punishes those who don't adhere to his idea of a basic social order. Maybe he's a teacher, a judge, or --" Katherine paused before winking at Elizabeth.

"... or a cop," the lieutenant finished the sentence.

Katherine chuckled briefly. "That's what you said. But he could also be a journalist. After all, he chooses his victims according to media reports."

"That would explain how he knew Kai Sawyer's identity," the lieutenant conceded, looking at her sister closely and expectantly. "Not bad, Kate."

Katherine could clearly see that she was flattered by her stern sister's praise. "As you know, I've been studying these people for so long that I almost think I can see inside their heads," she said before taking another sip of water. "Hence the title of my book."

Elizabeth took a deep breath and licked her lips. "So we're looking for an academic who resides in Boston, has or has had a cab license, and is in a profession where they follow or enforce rules. So, in the context of the rare pistol and the DNA evidence we're almost certain to find on Sawyer's body, Jack's days should soon be numbered. But you still owe me an answer."

There was silence in the conference room for a moment. Then Katherine thought she understood what the lieutenant was alluding to. "Who will Jack hit next time?" Elizabeth didn't even raise an eyebrow. "The people Jack has punished so far have burned other people's property, risked their own lives, exploited the social system, tortured animals, and lied to each other. I think he should start taking an interest in someone who harms his fellow human beings materially or physically. Browse the newspapers for violent crimes from Boston. Multiple offenders, if possible; that's what he finds most interesting. And they should be older than thirty, which is what his victims have all been so far. He identifies with this age group because he belongs to it himself."

Elizabeth didn't seem satisfied with Katherine's answer. Looking like she had just put the younger woman to the test, she took a step toward Katherine and said, "That wasn't the answer I meant."

Katherine now realized what the lieutenant was actually alluding to. "Of course, sorry. Yes, Nikki whispered to me that Maggie and you broke up. Why ... I mean ... What the hell happened. After all, your relationship was the paragon of steadfastness."

Elizabeth smiled sadly and lifted her shoulders. "I could say the same about you and Nick," she replied. Katherine frowned wide-eyed, her mouth open a little in surprise. Elizabeth decided to leave the subject for the moment. "Real life has happened, Kate. We'll talk about it in my apartment over a glass of wine tonight, okay?"

Katherine seemed surprised. "You have time for that?"

Elizabeth glanced at her smartwatch. "Maybe you'll develop a precise profile of Jack by then. Then, the meeting would be official. Just make sure you don't dress too businesslike."

Katherine rolled her eyes but smiled.