It was beginning to get dark, and a light rain was falling, the puddles of which refracted the foul yellow glow of the streetlights.

Nikki sat with Elizabeth and Katherine in Elizabeth's unmarked car on the way to Quincy Market. Nick had stayed at BPD, checking for suspicious chats or agreements on the forums Ben and Noah had been on. At the same time, he kept in touch with the FBI's IT department.

Jane had then realized that it would be better to continue the cooperation with the FBI that had already begun, especially if there had been such a murder in Boston.

It had indeed been a massacre. Nikki looked at the pictures from the market on her smartphone. Throats slit, like a second grin gaping in gruesome amazement. Pools and splatters of blood, a teenager on the floor, a vast pool of blood spreading further and further beneath him, the handle of a cleaver protruding from his head. What looked like a terrorist attack somewhere far away had happened here, here in Boston, and it looked like a gang of teenagers had committed it. All in black, all masked, all armed. That's what eyewitnesses had reported.

In Quincy Market, these youths had slit the throats of passers-by indiscriminately with box cutters.

Nikki saw the other pictures. The word they had read about on the BPD website. Slash Mob. The strange puppet master in the background, she thought. He gave his men instructions and made up catchy words for their massacres. After three people had been massacred, one of the eyewitnesses finally called 911. The youths had moved on, herding a mass of screaming, panic-filled people in front of them. When seven people were dead, Marc, Philip, and the RRT were called. They had made short work of them and shot three of the teenage attackers.

"Three of the perpetrators were shot?" Elizabeth asked, looking briefly in the rear-view mirror.

"Three or four." Nikki looked at her mother's silhouette. "They couldn't do anything against assault rifles with their box cutters. But they could go against the unarmed victims. Especially because it took people completely by surprise."

Elizabeth took a deep breath and frowned deeply. Slash mob, she thought. "Imagine that: You're standing peacefully at some food stall talking to your friends, acquaintances, or work colleagues, and suddenly someone comes along without warning and pulls a knife through your throat."

Nikki didn't want to imagine it, but she had to.

The car's radio crackled, and an officer relayed the direction of the getaway car he was following.

Two or three youths had parked an old VW van near Quincy Market. They had fled in it.

The lieutenant gritted her teeth. It was always a VW van, she thought. It was the favorite car of all American serial killers. "Where was the vehicle parked?"

"Near Quincy Market," Nikki said. "They had an easy time of it, of course. None of the shocked passers-by dared to stop them. The paramedics are already on the scene, as are the hearses. It looks like no one survived. If the carotid artery is severed, you bleed to death within minutes. The attack was just too sudden. And too deadly."

Katherine looked briefly over her shoulder from the passenger seat. "If someone cuts your carotid artery, three to five minutes is enough if nothing is done," she said. She was right. Not only because she was a doctor but also from her own experience, after a madman who called himself BodyCounter had shot her sister Elizabeth in the stomach in a cemetery and the lieutenant had only survived because Katherine had blocked the wound and thus the blood flow with her finger until the emergency services arrived on the scene.

Nikki's cell phone buzzed in her hand, and she furrowed her eyebrows. She had received more pictures.

Two young men, who looked like tourists, were lying on the ground, one on the other. One had probably gone down a little later. There was only a gaping red hole on both of them where the Adam's apple used to be. The ground was dark with blood. Three feet behind them lay more bodies. Forensics staff were on the scene and erected white tents over the bodies so that the MEs who had just arrived could work in peace and away from prying eyes. Gawkers had already pulled out their smartphones to record everything, and the media were already on the scene.

"The symbol," Nikki said aloud with a furrowed brow. "The symbol we've already seen in the train compartment and at the bus stop."

Elizabeth clasped her hands tighter around the steering wheel. "The chief will be very pleased," she growled.

Katherine pointed through the windshield at an armada of blue lights. "They're heading out of town."

Elizabeth nodded a little. "Let them. The fewer people in the way, the better."

Above them, a BPD helicopter rotated, its searchlight trained on the white VW van driven by the patrol cars.

xxx

Elizabeth watched her sister Katherine pace restlessly up and down the BRIC while Nikki and Nick pored over the teens' laptops.

Two boys and a girl, all under sixteen, had been arrested after the chase. At the same time, four of the perpetrators had been shot dead.

But the spokesman was still alive. It was a certain Herbert Mencer.

"Are they just confused teenagers who have formed a deviant group of killers on the net," Katherine muttered with furrowed brows, "or is there someone behind it? Is someone running this group?"

"I don't know," Elizabeth growled, following her sister with her eyes. "But it would serve everyone better if you stopped marching back and forth here."

"I just think better when I'm on the move," the psychiatrist explained. "Besides, I've just read a book about innovation in the Silicon Valley. Most ideas came to people when they were walking, not sitting around."

Elizabeth straightened up in her chair and opened her mouth, narrowing her eyes. She was about to ask her sister exactly what kind of book it was and why the hell Katherine was bothering with innovation in Silicon Valley, but then she decided against it and looked at her brother-in-law. "What's there to see on the laptops, Nick?"

Nick took a deep breath and looked briefly over his shoulder. "Everything blocked by proxy," he muttered.

The lieutenant frowned a little. "Proxy. I've heard of that before."

Nikki turned in her chair to face her mother. "It means something like deputy or intermediary. You can also think of a proxy as an intermediary, like a company whose employees all want to order the same lunch. Everyone can order individually, but if everyone orders Chinese anyway, the order can be passed on collectively. A proxy does something similar. Transferred to a network, this means that either every computer in a company directly accesses the external network, i.e., the Internet, or there is a central computer that receives and forwards requests."

"And why do our perpetrators need such a proxy?"

Nikki licked her lips and raised her eyebrows for a moment. "To prevent certain websites from finding out which country the user is from, for example. For example, some videos on YouTube are blocked due to copyright issues. But you can watch them in other countries. If the proxy thinks you're not from the USA, it lets you through, and you can watch the videos."

Elizabeth began to understand and looked at the monitor wall. There was a list of possible open proxy servers.

http/

http//proxy-lists.

Nikki turned back to the laptop she had been working on. "If we can find the open proxy servers, we might be able to get inside with a specific request. Or maybe not." She clicked through the pages. "This one is bad. Really bad."

Elizabeth stood up slowly from her chair and furrowed her eyebrows. "What did you do?"

Nikki smiled, but only briefly. "I made it clear to the server that I'm dialing in from Brazil, not Boston. Now we can watch the video."

The video was transferred from Herbert's laptop to the monitor wall.

A masked figure, whose face was barely captured by the camera, stood in front of a table on which a human body lay.

"She's dead, isn't she?" Nick asked with furrowed brows.

Katherine gritted her teeth. "Looks like it."

"Quiet," Elizabeth growled dangerously calmly.

The masked figure raised his voice. "Today, I will show you how to bone a corpse properly. Boning means cutting up. We have to debone the corpses so that the individual parts can be easily hidden. Let's take the elbow, for example." The man in the mask approached the corpse on the table and placed the knife on the elbow joint. "However," he continued, "the cutting or boning must be skillful. Take a look here. I put the knife on and cut the joint capsule, the muscles, and the ligaments." A sliding and then a snapping sound could be heard in the video. "Once we've cut through the joint capsule, all we have to do is cut through the muscle tissue and skin, like this," the man continued cutting, "and then we can easily remove the arm." He lifted the severed left arm of the corpse and held it up to the camera. "As you can see, you can now easily remove the forearm without having to go to the trouble of cutting or sawing hard bones. Special scissors, a pricker, a chisel, a hammer to cut the joints, and sometimes a file or a handsaw are also helpful, but you don't need any of that if you do it the way I do." He paused momentarily and then continued: "Make your killing just as easy. Don't use complicated weapons, but sharp, long knives you can get in any kitchen department."

Elizabeth pressed her lips together and gritted her teeth. She knew the unknown man was right. It was much easier to cut up a corpse if you used the correct technique. But that didn't mean everyone, except butchers, hunters, and forensic experts, should master this technique.

"Sometimes," the voice continued, "people die sitting up. Then decay gradually sets in, and the fly maggots hatch while the corpse sits upright. The soft tissue rots and, at some point, is just rotten sludge eaten by the maggots. And what happens then?" The man paused for a moment and then continued. "At some point, the head falls off, all by itself, because the exposed cervical vertebrae can no longer hold the heavy head without soft tissue connections. The head falls to the ground. People used to think it was haunted. But there were only two simple reasons: rot and gravity." He laughed softly. "That means for you: Anything that rots through on its own without you having to do anything can be cut through! Or, in other words, use predetermined breaking points!" The man with the mask leaned forward. A question had just been asked from offstage. "A chainsaw?" he asked. "You can use one, but it's deafening and makes a huge mess. Moreover, if you use a chainsaw a lot, you must keep the chain in oil overnight. How much does a sharp knife cost in the kitchen department compared to a good chainsaw? How much does a whetstone or simply a new knife cost? No, I'm sticking with it; my method of boning is the best."

Katherine looked briefly at her sister, who was now standing beside her. "He says deboning, not cutting or chopping. Boning is only said by doctors. Or people who are well versed in medicine."

Elizabeth pressed her lips together and nodded slowly. "That's what the kids in the VW tried. They cut off a corpse's foot. Partly, anyway."

"But not as well as the bastard in that video," Katherine replied with a furrowed brow.

"Right," growled the lieutenant. "The kids must have seen the video before, even if they didn't seem to understand it."

"The individual parts," the masked man in the video continued, "you can chop them up even further. It's best to make the body parts into small pieces and then put them in bin bags. It's best to dispose of them at an apartment building with large garbage containers. Ensure you do this on Monday evening, but not so late at night that anyone gets suspicious. On Tuesday morning, the garbage collectors will come and take everything away. And you'll be rid of your worries. And the body, too."

Nikki looked at her laptop and frowned a little. "Something else has come in here."

Elizabeth took a deep breath. "From who?"

"From the FBI's IT department.

"It looks pretty complicated, what the FBI cracks sent you."

Nikki nodded slowly. "At first glance, yes. They analyzed all the posts to see if they could be traced back to a specific person. They ran some algorithms and did variance analysis on the accounts of the different killers. That's the lowest common denominator. So this person must be the key."

Elizabeth lowered her head and massaged the bridge of her nose. "Now get to the point, Nikki. Who is this key?"

Nikki got up from her chair and walked to the monitor wall, pointing at it. "There's an element that connects all these kids. A kind of common code. They've all had various conversations, chats, and emails on the dark web, the clear web, and 4chan with one person."

Katherine sensed that her sister was losing her patience and cleared her throat. "And what's the person's name?"

Nick looked at his wife and frowned. "At the beginning, we only knew the person as GOB666."

Elizabeth furrowed her brows. "Is this the GOB666 we've seen before?"

Nikki pressed her lips together and nodded slowly. "Yes, and that shows us this 'anatomy' lesson.

Elizabeth licked her lips slowly. "At the beginning, GOB666. What do you mean, at the beginning? And now?"

Nick gritted his teeth and frowned deeply. "But now this person is completing the abbreviation into a full name."

The lieutenant looked at him for a long time. "And the name is?"

"God of Blood."