John was glad that he didn't have to go into the clinic the next day, as he was so exhausted he slept until ten in the morning. As soon as he woke up he reached for his mobile and dialed Sarah. "Do you know how to get hold of Dr. Arthur?" he asked as soon as she picked up. "Some records the Yard showed us yesterday had his name on them."

"I can give him your number and tell him to ring you, but I don't know if I can just give his number to you," she said. "Is whatever you saw in the records something you can discuss?"

"His name was on some of the reports. He also put in a statement that he thought the father of one of the victims was the culprit." John felt that was a safe statement to make.

"All right. I'll say it's a police matter and hopefully he'll get back to you. I'll see you on Monday?" The last part had an unstated "if you're not running somewhere with Sherlock on a case" clearly attached.

"You will," he said before disconnecting.

After showering and getting dressed, he went downstairs. Sherlock was nowhere to be seen, although whether that was because he was still in his room or because he had taken off earlier he didn't know. Maybe he had already headed out to view the area that flat was in. Whatever the reason, he was glad for the quiet as he made tea and several slices of toast.

John had almost finished his breakfast when he heard a noise from the stairs. Sherlock appeared within a minute, wrapped in his dressing gown, a blank look on his face. Something about the way he looked made John refrain from telling him "good morning". The silence that hung in the air as Sherlock sat down on the couch and stared off into space wasn't much better.

Finally, unable to stand the quiet any longer, John said, "Are you going to wherever that flat is today? And are you just going there? It might be a good idea to talk to the landlord before doing anything else. At least you should call whoever it is after finding the building."

Sherlock's only response was a grunt of acknowledgement.

"I rang Sarah and she's going to give my number to Dr. Arthur, so he can get in touch with us," he tried this time. Still no response, and John felt a twinge of unease. "Sherlock?" Nothing. "You don't have to do this all at once," he added. "You're allowed to take a few days off."

"I'm going today," Sherlock responded, his voice flat. It was like all of the emotion had been bled out of him.

"To where the flat is?" John asked.

"Yes. Of course." He didn't elaborate.

"Are you still worried about Phillip?" John wasn't sure of the right way to broach the subject. Sherlock didn't do emotion, for the most part. Of course that didn't mean he didn't have feelings; John knew better than anyone else that the whole "high-functioning sociopath" bit was a cover for feelings he refused to express. But he kept his emotions so close to himself that it made whatever he felt barely register. Maybe it was just the personal connection, but this case had unwound him. Suddenly Sherlock was tender, rageful, saddened. And afraid.

"He is one of my primary concerns," Sherlock responded after a minute or so.

"You can worry about yourself, too," John reminded him.

Sherlock got up from the couch, like he hadn't heard him. "I expect us to be leaving for the general area by noon. I trust you will be ready then." He vanished into the stairwell and after a few minutes John could hear the shower running.

The shower ran for a good portion of the time before they left. John knew better than to comment on it, or ask about it in the first place, but not for the last time he wished he could just sit down and talk with Sherlock about the bee incident, the case, and everything else he hid behind that brick wall. However, he couldn't help but comment on the rubbish bag Sherlock had slung over his shoulder. "What's that?" he asked.

Sherlock looked at him for a second, damp hair falling in his face as he did so. "Rubbish," he told John, in a way that made it clear he didn't want to talk about it. And although that just made John even more curious about whatever he was throwing away, he said nothing as they left the flat and Sherlock chucked whatever was in it in the nearest bin. He knew that by the time they returned home it would be gone, and even if it wasn't John wanted to respect Sherlock's wish for privacy. True, Sherlock never respected his own, but he didn't think that sort of thing had to be reciprocal. Shortly thereafter Sherlock hailed a cab and John's train of thought was brought to an abrupt end.

The neighborhood where Sherlock apparently had placed this flat was in fact near the Aherne's flat, and they even passed by that building on the cab ride there. The driver stopped in front of a nearby playground that was probably the one Moira Aherne had taken her dog to. Sherlock scrambled out right away, and John followed him after giving the driver the fare. Once the cab was gone, Sherlock turned in a circle, eyes wide open. He then cast his eyes up the street. "It's just up there. Come on, I want a closer look at the building." He sounded more like his normal investigative self, which made John feel slightly better.

In a few minutes both of them were standing in front of what seemed to be a perfectly ordinary building. John couldn't see anything that made it somehow stand out from the ones around it, but he did notice that in the visible ground floor flat all the windows were covered by curtains. Sherlock headed towards the front step without saying anything, and tilted his head so he could better examine one of the windows.

Suddenly, the front door opened. A short, petite woman with graying hair emerged.

"Hello, did you come about the flat on the third floor? It's still available. Quite a lot of people have come to look at it, but I'm the one that makes the final choice." She looked down the walkway at John. "Are you with him? Come over here, don't be shy. Better for anyone who's going to live there to see what it's like."

John took her advice, sort of, and walked up to the front step where the two of them were standing. "We're not here to see the flat," Sherlock said with authority. "Are you the landlady? I'd like to ask you some questions about your tenants."

The woman looked up and down at Sherlock before she said: "Ask away. Please keep in mind I've only managed this building for five years, so I can't tell you any farther back."

"Why are all the curtains drawn on that ground floor flat? Is the renter a night shift worker?" He sounded like he had no idea who lived there himself, and was just asking because he was curious.

"No idea," she said matter-of-factly. "My mystery tenant is there."

"What's so mysterious about this tenant?" Sherlock inquired.

She raised her eyebrows before she spoke, like she wasn't sure he'd believe her. "All I know is that the person who rented it made the offer before my time. In the past five years I've never seen the renter at all. Other people in the building have heard noises in there, and the few times I've gone in there myself I've seen some furniture and odds and ends, but never a person. Very odd. The tenant - a Dana Lester - sends me checks every month like clockwork, so it's not like I can evict them, and the flat's always clean."

"Do you have copies of those checks on file?" John broke in. At the very least it might be something K could be traced from.

"Yes I do, young man, but those won't be much help if you're looking for this Dana Lester. All starter checks. You boys don't really remember when everyone had to write checks, but the bank would always give you a few of them without a name or address on them to get you started. No store would take them, but you could still use them for individual people. And the numbers are always different after about eight of them or so. Whoever Dana Lester may be, they make sure to cover their tracks." She nodded sagely. "I sometimes wonder if all that isn't on the up and up, but there's nothing in the flat that would tell you that."

"Can we see the flat, at least?" Sherlock asked.

"Of course you can. If something isn't right there I'd want to know about it. I'll take you boys in." The woman led them through the door and towards the door of the ground floor flat. She selected one of a ring of keys and opened the door. "Hello?" she called as she stepped through the door. "It's the landlady, Mrs. Murray." No one responded, but neither John nor Sherlock seemed surprised by this. They walked in after her.

The first thing that John noticed was the minimal furniture. It wasn't a particularly large flat, so there wasn't really room for a lot of belongings, but all that was in the living area that bordered the kitchen was a couch, a throw rug, and a coffee table. The kitchen had no microwave, or for that matter any other appliances; all that was there was a stove, refrigerator, and some cupboards. The second thing was how clean it seemed. If K really didn't live here, he still had to put some effort into cleaning the place. Of course, if he really brought his victims to this place cleaning it would effectively remove most evidence. Mrs. Murray shook her head in silent disapproval before leading them down the hall to the one bedroom. It was also furnished minimally; there was only a king-size bed with no headboard or footboard tucked in the corner and a chest of drawers. There wasn't even a bedside table with a lamp and a clock. Sherlock strode up to the bed and bent over the covers, sniffing audibly. "These sheets were recently washed," he said. "Is there a laundry in this building?"

"No laundry, but this flat has a washer and dryer." Mrs. Murray stepped out of the bedroom and opened the other hall door, which revealed a washer and dryer stacked on each other. "The only laundry nearby lost a few of my things right after I moved in here, so I made sure the tenants all had their own. Of course my mystery tenant already had a set."

"Very convenient," John said in a tone heavy with meaning.

"Well, I try to make the lives of the people living here easier," Mrs. Murray told him, and John wasn't sure if she hadn't caught his meaning or had but was choosing to ignore it.

Sherlock took a few more circles around the flat before nodding to himself, apparently satisfied with something. "I don't think there's anything more to be seen here. Mrs. Murray, I know you said before you have copies of all the starter checks Dana Lester has given you. Do you have those here right now?"

She nodded. "They're in my flat on the second floor. I'll go and get them for you." After a few minutes she returned with a manila folder in her hands. "This is everything; the checks but also anything else I noticed about my little mystery tenant. As I said before, I'm not sure it's all on the up and up but the rent was paid every month and the checks never bounce so it's not like I can ring up Scotland Yard and tell them that my tenant only pays me with starter checks."

"Very smart of you," John said with approval. Clearly this Mrs. Murray didn't miss much. Sherlock took the folder from her hands and was beginning to look inside it when John's mobile rang. He brought it out of his pocket and put it to his ear. "Hello?" he asked.

"You must be Dr. Watson. This is Dr. Ronald Arthur, and I was informed by your co-worker that you wanted to speak to me on an official police matter?" Dr. Arthur's words were polite but the tone he used indicated he resented whatever John wanted to ask before he did so. He sounded like the sort of physician who thought their medical degree made them superior to the rest of mankind.

"Yes, me and my friend Sherlock. He works for the Yard," John replied.

"Well, right now I'm back at Bart's to collect some things Sarah saved for me, and if you can be there in an hour or so I suppose I can speak to the both of you." The fact Dr. Arthur had addressed him by title but had referred to Sarah by her first name was not lost on him. There could be several reasons for that, but John felt it was probably the old failsafe reason "he's a sexist git". That would explain why Sarah apparently held him in such low regard.

"We'll be there in an hour," John promised, and hung up. Sherlock looked up from the folder to him. "That was Dr. Arthur. He's at Bart's right now and said if we get there soon he can speak to us."

"Excellent. I need to ask him some very important questions." Sherlock sounded completely like himself again, and that was a relief.

"I can't let you boys leave without something to eat," Mrs. Murray told them. "If you'll wait a minute I'll bring you some dinner."

"That would be good, thank you," John said before Sherlock could object. He was hungry and knew better than to think Sherlock would want to go anywhere besides Bart's when they got out of here. Mrs. Murray soon returned with a large brown bag that smelled of cooking oil.

"Fish and chips, of course. My oldest grandchild is coming by and she's always been a fan of my fish." She handed the bag to John and then patted him on the shoulder. "Now keep me updated on whatever Dana Lester's been up to; it's not very fair if I don't get to find out the end of the mystery. You boys take care."

Once the two of them were seated in a cab on their way to Bart's, Sherlock spoke up. "K works the swing shift. It's probably not a full time position, but that makes little difference to K. K was born wealthy."

John stopped halfway in the process of bringing a piece of fish to his mouth. "I suppose K must have some additional means of income to keep up a flat he doesn't actually live in, but where did all that come from?"

"K is easily able to reach the Aherne's flat at night despite not living in the area. If K worked a normal day shift position there would be a risk of being seen in the area before nightfall. K keeps the second flat well maintained but can't be seen there too often. Therefore K either brings victims there before the day shift ends, so adults are not at home to witness them but children are already out of school, or after the swing shift is over. Phillip, and presumably several other victims, come from homes where they would not be missed in those hours; distant or abusive parents, and single parents who work night shifts. They are the ones who will spend the night at the flat, and of course all of them appreciate the closeness that results. Moira would be missed if she vanished and as a result K decided entering the flat through the window at night would be safer. K's furniture in the other flat is minimal but well-made. Oak, not quite antique but older items of high quality. K must have no sentimental attachment to them since K doesn't feel the need to keep them in residence. They are obviously discards from a collection of furniture, likely from K's parents. If K's parents no longer need them, they are presumably not alive, and if they were wealthy enough to buy these pieces when alive K would have inherited a significant amount of money on their deaths." He stopped for a moment and looked out the window, one hand turning white-knuckled on the folder as he grasped it.

"What about the starter checks?" John asked. Truthfully he wasn't sure they had any relevance at all, but it was such a strange detail it stuck with him.

"K periodically starts checking accounts and closes others. Doing so enables K to have a constant string of starter checks with no identification on them. K uses false identification to open and close these accounts, of course, and has probably used that false identification to obtain credit cards in their names. This also gives K plenty of resources if a victim dares to speak and ample means to flee the country. All of these things point to some form of independent wealth. If K had worked for all that money K would still have many demands at the job, even at a position passed on from parent to child or one that was largely a figurehead position."

"He's prepared for almost anything," John said with a faint sense of horror. If K was really so careful it was going to be hard to catch him.

"Our advantage is that K does not know at this time about the investigation, or the flat would have been vacated. K washes the bedding on the one bed every time a sexual encounter occurs so no forensic evidence is left. The fact that something like that is still going on, even after the incident at the Aherne's, indicates that K is confident no one will talk or has talked." He now had both hands in a white-knuckle grip on the folder.

"I presume Dana Lester is an alias?" One good thing about Sherlock's long deductions was that John had plenty of time to eat while he spoke.

"Of course, one of many. I would not be surprised if K had several flats for sexual encounters." He looked out the window then, and John fully expected him to start talking about K again, but he remained silent on the rest of the ride to Bart's. John ate the rest of the fish and chips in silence.

John led the way into the clinic, hoping Sarah would know where Dr. Arthur had decided to wait for them. She spotted him before he saw her, and waved to him. She ducked into an examination room and John followed, Sherlock trailing silently behind. "Thank you for getting here, John. If I have to hear that man tell one more idiotic 'joke' I'll be part of your next murder investigation." She raised her eyes to the ceiling. "I hope he gives you some good information, but mind you he can be very certain about things, no matter the facts. I remember when a well-known child psychologist was due to give a lecture here, Dr. Tracy Newsome, and Dr. Arthur kept going on about how he wanted to talk to him. Bit of a shock when he was face to face with Dr. Tracy Alice Newsome," she added, clearly amused by the memory. "Anyway, he's in the conference room on the second floor. You know where that is."

"Yes I do. Let's go," John said and once again led the way. Sherlock followed but appeared lost in thought, like he was in the midst of yet another deduction. Hopefully he wasn't so lost that he wouldn't question Dr. Arthur, since John had no idea what he should ask the man.

Dr. Arthur was seated at the head of the table, even though he was the only person in the room. He was dark-haired and immaculately dressed, like he had been cut and pasted from a magazine. "Dr Watson?" he said as John and Sherlock went into the room. "Dr. Arthur." He extended his hand and John shook it (it felt like shaking hands with a pickled herring) but when he extended his hand to Sherlock all Sherlock did was glare at him. Looking offended, he sat at the head of the table again. "What is this investigation you're asking me about?" said Dr. Arthur, who was obviously trying to regain his composure.

"It's an abuse investigation," John supplied. "A serial sexual offender who hasn't been identified. Two patients you examined in the A&E have been pinned down as possible victims, Sagnik Malakar and Jennifer Ogbeide-Bena. Do you remember them?" He pulled out a chair for Sherlock, but he didn't sit down and continued to rock on the balls of his feet. Dr. Arthur looked disgusted.

"The boy was the one that didn't speak much English, if I recall. He said he'd been picked up in a car and taken to a flat where he engaged in sexual activity with the person driving the car. There were translation issues, if I recall." He kept his eyes fixed on John, seemingly ignoring Sherlock's presence in the room.

"Did he tell you anything about the perpetrator?" Sherlock spoke up.

"Not much, truthfully." Dr. Arthur was still looking at John, like he had been the one to ask. "He said the car was blue and the flat was clean, but he seemed dazed."

"Did you draw his blood for drug testing?" Sherlock looked him in the eye. "If he was dazed it could have been from administration of a benzodiazepine."

Dr. Arthur had the grace to blush as he said: "No, I'm sorry, that didn't occur to me. It was hard to tell if he was truly out of sorts or just had poor English skills." He sounded dismissive, and John figured he could add "prejudiced" to his mental list of traits of Dr. Arthur.

"Because he was from Bangladesh, of course any communication issues had to be a matter of intelligence or language skill." It was clear that Sherlock was scornful, probably for the same reason John was starting to dislike the man.

"Perhaps. He had no injuries other than some mild bruising of the thigh and shoulder. That's all I remember from his case. You mentioned another child?" He sounded eager to change the subject.

"Jennifer Ogbeide-Bena," Sherlock confirmed. "Brought here by her father. You stated in your report that you felt her father was responsible."

"Oh, yes, I remember that case. There were some signs of sexual abuse on the exam, mostly reduced rectal tone and a patent vagina. Father claimed she'd said a lewd phrase to him, which made him come to the A&E with her. There was a custody battle at the time as well, with the mother." He seemed pleased he remembered that much, almost like he wanted to get credit from Sherlock for this.

"That's in the record," Sherlock said dismissively. "You placed a report saying the father was the suspected abuser. Why did you say that? The girl never told anyone about that."

"Well, the father was fighting the mother for custody. A man who wants to take a little girl from her mother? It doesn't make sense. Also, the perpetrator was probably someone known to the child, and statistically it was most likely to be the father." He seemed pleased with his logic.

"Statistics are all well and good, but did you have any evidence that the father was responsible besides the statistics?" Sherlock's gaze burned into Dr. Arthur.

"The girl was so reluctant to talk about who had hurt her 'down there' that it made me suspicious. The father would be the person who she would most want to protect."

"If he really was the one abusing her, why did he bring her here? You stated yourself it was because of something obscene she said, not because he saw any physical injury." John wanted to cheer Sherlock on but did not. Still, he couldn't deny there was a certain pleasure in seeing him savage Dr. Arthur's logic.

Dr. Arthur rose out of his chair, not quite at eye level to Sherlock. "He presumably wished to blame it on the mother's boyfriend or someone who was important to her," he snapped.

"If he was intending to do that he did a remarkably bad job of it, since he said on the record he had no idea who might have taught her to say that. He said her mother had a drug habit but wasn't seeing anyone." In contrast to Dr. Arthur's outburst, Sherlock seemed calm and collected.

"Enough! I have explained my reasoning to you already! If all you can do is attack me then this conversation is over." Without another word but clearly seething with rage, Dr. Arthur stormed out the door and into the confines of the hospital. Sherlock watched him walk away with a small smile on his face. Apparently the conversation had been helpful to him at the very least.

"Jennifer's father, the one who wants to speak to us, Michael Ogbeide. He's also an immigrant. The records said he came here from Sierra Leone as a teenager," he said with satisfaction.

"So Dr. Arthur assumed some foreigner had to be responsible, because he's a racist and sexist git," John added. "Now I know why Sarah had so many horror stories about him."

Sherlock looked like he was about to comment further, but at that moment his mobile rang. "Lestrade?" he said as he brought the device to his ear. "Oh, that's good. When does he want to meet with us? Next Friday? I'm sure that can be arranged." He hung up. "Speaking of the man, he got in touch with Lestrade and said he was coming to the Yard next Friday and he's willing to speak with us."

They started towards the lift. As they were waiting, John commented, "I hope you were recording that conversation with Dr. Arthur, just for the record." Sherlock grinned wickedly and reached into his coat pocket, pulling out the same tape recorder he had used for Moira's questioning. Suddenly all this seemed hilariously funny, and John burst into peals of laughter. Sherlock looked at him for a second before starting to laugh himself. It was a relief to have something to laugh about. John was glad for anything that diffused the horrible nature of the crime, and Sherlock more than anyone else needed something to laugh at.