A/N- *pops up from underneath the desk* Hello, lads and lassies! Back for more already? Well, here. Take it and like it! Or don't, your choice.

Disclaimer: I only own my OC. If I owned Sherlock...you'd probably still have to wait two years for new episodes because I'm a black belt at procrastinating.

Enjoy!


"I still don't know how you managed to convince me to bring Harley along…again," John grumbled for the umpteenth time as they drove through the London streets later that morning.

"Because you'd be leaving her at the flat to fend for herself because Mrs. Hudson is over at Mrs. Turner's today, whereas she could be useful here," Sherlock answered offhandedly. "I fail to see why you insist on repeating this conversation."

Meanwhile, Harley sat in the middle between the two men, feeling like she was watching a tennis game back and forth…and kind of feeling like a third wheel. She hardly found herself being useful at the moment, other than Sherlock had given her the duty of holding his laptop to take to Scotland Yard.

Yeah, so useful, she thought wryly.

"It'd still be better than you dragging her along on one of your crazy, not to mention sometimes dangerous chases," said John.

"We're just going to the Yard, John. Honestly," Sherlock said, rolling his eyes.

"And after that?"

A pause. "…Brian Lukis' flat, if we can convince Dimmock."

John threw his head back in exasperation.

"It's not like his body's going to be there this time, John," Sherlock argued before John could say anything. "Besides, you don't hear her complaining, do you?"

That caused both the Watsons to look at him with serious expressions.

Oi, wrong choice of words there, buddy, she thought.

Sherlock sighed. "You know what I mean."

John turned his head and looked out his window, muttering to himself but dropping the subject for now. Harley looked away as well, shaking her head. Of course she knew what he meant, and in a way, he was right. She really wasn't complaining. In fact, she actually got kind of excited when he told her to get ready before they left. She found that quite curious. He didn't ask her if she wanted to come; he practically ordered her to, like he knew she wanted to come so he just told her so without bothering to ask, despite John's protests. And so she did.

And that was how Harley ended up in the back of a cab in the middle of the morning once again, most likely diving headfirst into another misadventure with her uncle and the consulting detective — the killer who can walk through walls had struck again.

This was certainly going to be quite a story to tell when she's asked to write an essay about her holiday at school.

Several minutes later, they pulled up in front of New Scotland Yard, which was a large business-like building consisting mostly of windows for walls, the metal sign out front revolving around. Cool, Harley thought as they jumped out of the cab and went in. She had never been to Scotland Yard before, but has heard of it countless times. This was going to be interesting. She didn't really have time to admire the place, though, because Sherlock practically ran through the building, hardly slowing down. John and Harley had to jog to try and keep up with him, Harley keeping his laptop firmly tucked under her arm so she wouldn't drop it. She barely had time to process the many police officers who sent them odd looks as they rushed by.

A few floors up, they finally caught back up with him, where he was already pestering Detective Inspector Dimmock at his desk. Knowing he wasn't going to wait any longer, she pulled out his laptop and handed it over to him. He logged in and went back to the online news article from earlier. Dimmock crossed his arms in annoyance as he watched.

"Brian Lukis, freelance journalist. Murdered in his flat…." Sherlock said as he swiftly turned the laptop around to show the scowling DI. "Doors locked from the inside."

"You've gotta admit, it's similar," John added. "Both men killed by someone who can…" he hesitated momentarily as if unable to believe what he was going to say next, "…walk through solid walls."

Naturally, Dimmock sent a disbelieving look John's way.

Who you gonna call? Harley thought.

"Inspector, do you seriously believe that Van Coon was just another city suicide?" Sherlock asked. When Dimmock only squirmed in his seat, not meeting his eyes, he looked up and sighed in exasperation. "You have seen the ballistics report, I suppose?"

Dimmock finally looked up at him, his jaw tight. He nodded.

"And the shot that killed him, was it fired from his own gun?"

"No," the DI answered reluctantly.

"No. So, this investigation might move a bit quicker, if you were to take my word as gospel," Sherlock snapped at him.

There was a moment of silence as Dimmock shifted uncomfortably in his seat. Harley wanted to feel sorry for the man, but come on, how much more proof did he need that these guys were getting offed? Plus he tried to kick her out of the crime scene. Big no-no.

Sherlock leaned forward over the desk and said quietly but intensely to his face, "I've just handed you a murder enquiry." He nodded down at the article of Lukis, speaking at normal volume again but his tone still just as firm, "Five minutes, in his flat."

With a deep sigh, the Detective Inspector relented in his stubbornness and followed them out of the station, taking his own police car while Sherlock and the Watsons hailed another cab. They soon arrived at Brian Lukis' flat, ducking under the yellow police tape at the bottom of the stairs. Lukis' flat was not nearly as nice as Van Coon's was; it was more congested and cluttered. Harley was careful not to knock down the many books stacked unceremoniously to the side of the staircase as they went up.

When they entered the room, the first thing she noticed was the open suitcase on the floor just to the side. Harley frowned. Wait…didn't Van Coon have a suitcase out in his flat too? And if that wasn't enough of a coincidence, nearby the suitcase there was a small, black paper flower— exactly like the one Sherlock pulled out of Van Coon's mouth. More books were everywhere on the desks and shelves, newspapers scattered all over the floor. Lukis having been a journalist, it wasn't very surprising, though.

But what Harley didn't understand was why he was killed in a similar fashion as Van Coon— someone who worked at an investment bank. They had no connection career-wise. Did they know each other somehow? She didn't think so. And again, how were they killed if there seemed to be no other way in?

Sherlock strode over through the kitchen, going to the window and looking out through the curtain. "Four floors up," he said with a smirk, "That's why they think they're safe. Put a chain across the door and bolt it shut; think they're impregnable." He turned back and walked into the middle of the room, looking around the room once more. "They don't reckon for one second that there's another way in."

Harley glanced at him inquisitively. So he was wondering the same thing too. She looked around this flat more closely, trying to find out if there was another way of entry that they missed. Everything seemed bolted shut, locked tight. Then she turned and walked a few paces until she stood in the doorway to the staircase again. Her gaze lifted until it landed on the skylight in the angled ceiling just above the landing. The only thing attached to it was a prop to keep it open on a nice day. No bolts. No lock.

She squinted. Wait, could that…? She gasped. It could!

She whirled around to get Sherlock's attention, only to find him looking up at the skylight as well. He caught her gaze, his eyes widening slightly, and then he smiled.

Yes, he sees it too!

Without a word, they rushed out the door onto the landing.

"I- I don't understand," Dimmock said as they darted past him.

"We're dealing with a killer who can climb," Sherlock explained as they stopped underneath the skylight. Sherlock stepped on one of the boxes to get closer to the window. Harley watched from underneath him.

"What are you doing?" Dimmock asked as he and John looked on.

"He clings to the walls like an insect," Sherlock told him. He pushed on the latch, opening the window upwards. "That's how he got in."

"What?!" Dimmock asked, looking between Sherlock and Harley in disbelief.

"Climbed up the side of the walls, ran along the roof, dropped in through this skylight."

Harley took in the size of the skylight window, the length and width. Whoever had snuck in would've had to have been small, like her, to fit through, and very light on their feet if they were able to come in undetected.

"You're not serious! Like Spiderman?!" Dimmock exclaimed.

Harley stared pointedly at him. Seriously, what is your problem, man?

Sherlock turned to look at him as well. "He scaled six floors of a Docklands apartment building and jumped a balcony to kill Van Coon," he insisted.

"Oh, ho- hold on!" Dimmock laughed in disbelief.

"And of course, that's how he got into the bank. He ran along the window ledge and onto the terrace."

Harley thought back to when they were in Sir William's office at the bank. She had a theory that perhaps there was the slight chance that the person had climbed up and came in through the window, but had dismissed it. So that meant…

"Yes, Harley," a voice brought her back to the present. She looked up at Sherlock, who stared back down at her. "You were right."

She blinked, then instantly looked away. He…saw her looking?

Sherlock stepped off the box, Harley backing up to give him more space, and he looked around again. "We have to find out what connects these two men," he muttered, mostly to himself. His eyes then fell on the pile of books on the staircase, his gaze sharpening as he spotted something. He jumped down a few steps and picked up one particular book — a red hardback novel — that had been left open on the front page. Harley took a peek at the book and saw that there was a stamp on the front page marking that it was from the West Kensington Library. Sherlock then slammed the book shut, tucked it under his arm, and started to head out. Harley and John quickly followed suit, knowing they now had a new lead. Harley wasn't sure what they would find at this library to help find out who killed the victims, but she figured that it was better than nothing.

Luckily, the West Kensington Library wasn't that far from Lukis' flat. A short cab ride later, they had pulled up to the library and went in.

The second Harley did so, the first thing that went through her head was, Oh…my…God.

Having only been limited to her small, scarcely funded school and local library where she lived, the West Kensington Library was by far the biggest, most impressive library Harley has ever set foot into. Books, of every genre; everywhere she looked….and there was more than one floor of them!

Am I dead? Because I think I've just entered heaven!

John looked over at his niece and laughed at her star-struck expression as they rode the escalator up to the next floor. "Now, Harley. We're not here for browsing," he joked. "Just promise me you won't take off here, never to be seen again?"

Harley looked at him flatly as they made it to the top. She took her notebook and wrote for him:

Sure thing, Uncle…if you promise not to try and get off with the lady at the information desk.

John frowned at the note, then looked at her sourly. "Touché," he said slowly.

She smirked.

"If you two are done with your bantering now…" Sherlock called back impatiently as he continued to walk briskly across the floor toward the desk ahead. Harley and John sent each other a mock glare before catching up with him. Sherlock opened the book to the front page, running the bar code under the scanner. Then the computer next to it showed where the book was categorized under, which section it belonged in at the library, and when it was last checked out, which was yesterday. They left the desk and started going down one of the many aisles of shelves.

"Date stamped on the book is the same day that he died," Sherlock said, checking the reference number on the spine of the book before he stopped, looked up, and started taking out books from the shelf nearest him.

Harley had seen the reference number herself, and as someone who spent most of her free time away from other people in the confines of a library — learning how the basic system worked over the years — the only thing that she thought as she watched Sherlock take out the books was, Psh! Amateur.

Shaking her head, she turned to John and pointed at a row of books three shelves up just across the way on the opposite side of the aisle where Sherlock was searching; spotting the reference numbers on the spine that was closer to the one they found in Lukis' flat.

"You sure?" John asked her.

She scowled at him. Are you testing me, boy?

John put his hands up in surrender at her look, and they started taking out books by the handful on the shelf. When they did, they were instantly greeted by a familiar bright yellow color curved in a certain design on the back wall of the shelf.

"Sherlock," John called.

The sleuth came over to them and, seeing the splash of yellow, he pulled out as many books as he could with one hand and handed some of them over to Harley, revealing more of the paint. They were the exact same symbols that they had found in Sir William's office at the bank. Sherlock immediately took out his phone and started snapping pictures of it, staring intently at it as if trying to make out what it could mean.

And so the plot thickens, Harley thought ominously.

Once Sherlock was finished, they placed the books back where they found them (by Harley's insistence. What, were you raised in a barn? Show the librarians some decency!) and they left the library. They ended up heading back to Baker Street. Once in 221B, Sherlock went straightway to his laptop after Harley handed it back over to him, downloading the pictures from his phone and printing them off before adding them to the growing collage around the mirror on the wall. Sherlock and John had taken their coats off. Harley, however, kept her jacket on. She had a sinking feeling that they weren't going to stay for very long. From the way she's seen how things operated around here, once Sherlock gets another lead, they most likely were going to charge off again. Best not to get too comfortable, if that was the case.

The three of them stood together in front of the fireplace, staring at the photographs on the wall.

"So, the killer goes into the bank, leaves a threatening cipher for Van Coon. Van Coon panics, returns to his apartment, locks himself in. Hours later, he dies," Sherlock explained.

John spoke up next, in a softer tone, "The killer finds Lukis at the library. He writes the cipher on the shelf, where he knows it'll be seen. Lukis goes home…"

"And later that night, he dies too," Sherlock finished.

Harley tilted her head to the side, eyeing the pictures fixedly. What astounded her the most was how the killer knew exactly where to put those symbols where their target would easily see it. How did they know Van Coon would see the cipher from all the way across the trading floor on that painting? How did they know Lukis would pick out a book on that precise shelf where he'd find it? And again, what connected these two men, and why were they killed for it?

"Why did they die, Sherlock?" John asked in a whisper, unknowingly voicing Harley's thoughts.

"Only the cipher can tell us," Sherlock answered. He ran his finger along a photo of the symbols and tapped it a few times pensively. Suddenly, his gaze sharpened. He turned and started to put on his long black coat again, intent on taking off.

And there it is.

John sighed and proceeded to put on his own coat. Harley just stood by the door, waiting for them.

"Already catching on, are we?" Sherlock remarked, eyeing her.

Her lips quirked as she nodded. Ee-yup!

John shook his head with a groan, as if thinking, Dear God, what did I just get my niece into?

But she didn't care. She was actually having fun, if anyone could believe that. She wanted to solve this mystery now. She followed the boys downstairs. Yet another cab ride later, she suddenly found herself walking through the crowded center of Trafalgar Square, heading for the National Gallery. Harley had been there already once, on her second day with her uncle. So this was going to be a treat, coming a second time to see how this would help with the case.

"The world's run on codes and ciphers, Watsons," Sherlock explained to them as they strode through the square, passing fountains and marble statues. "From the million-pound security system at the bank, to the PIN machine you took exception to…" Harley nudged John playfully in the ribs at that, and John shot her a look. "…cryptography inhabits our every waking moment."

Harley couldn't help but agree. It seemed everything about the world today and their very lives seemed to be stored in a vast computer system, leaving no secrets, no stone unturned. It sounded unsettling when you put it in that perspective. Maybe that was one reason she found solace in reading paper-bound books; they never put her out there or judged. They just told a story or taught information. Simple as that.

"Yes, okay, but…" John trailed off, and Sherlock finished for him.

"…But it's all computer-generated. Electronic codes, electronic ciphering methods. This is different. It's an ancient device. Modern code-breaking methods won't unravel it."

"Where are we headed?" John questioned as they climbed up the steps toward the National Gallery.

"I need to ask some advice," Sherlock answered, rather reluctantly, like he had to struggle with admitting it.

"What? Sorry?" John asked, smiling in disbelief.

Sherlock sent a dark look his way. "You heard me perfectly. I'm not saying it again."

"You need advice?"

"On painting, yes. I need to talk to an expert," he told them as he led them to the entrance of the gallery. However, instead of entering the large building, he swerved and started to lead them around the building until they reached the abandoned rear of the building— well, not completely abandoned. There was one person there, and Sherlock walked straight up to him. It was a young man in street clothes, a teenager by the looks of it — maybe a few years older than Harley — who was spray painting an impressive-looking stencil art on a large metal door with spray-paint cans in both hands. At his feet was a canvas bag filled with even more used paint cans. The image he was creating was a policeman with a pig's nose and a rifle in his hands. Underneath the artwork was a tag, "RAZ". Probably the name he went by.

"Part of my new exhibition," he said as they approached him, putting the finishing touches to his work.

"Interesting," Sherlock said, with hardly any interest, as he reached into his pocket for his phone. Harley went to stand next to him, getting a good look at the graffiti.

"I call it, 'Urban Bloodlust Frenzy,'" the young man said with a proud chuckle.

"Catchy," John commented.

Porco Rosso has become what he despised the most. 'Tis a dark day for all of us, Harley thought gravely, but nonetheless, she couldn't help but admire the effort and talent put into it. The boy was an artist— a vandalism artist, but an artist nevertheless.

"I've got two minutes before a Community Support Officer comes round that corner," said Raz, turning to Sherlock. "Can we do this while I'm working?"

Sherlock held out his phone to him, the pictures already on the screen. Raz tossed one of his spray-paint cans to John, who caught it out of reflexes, and took Sherlock's phone.

"Know the author?" Sherlock asked as Raz started scrolling through the pictures.

"Recognize the paint," Raz said. "It's like Michigan; hardcore propellant. I'd say zinc."

Harley's eyebrows rose, impressed that he knew what kind of paint the killer had used.

"What about the symbols? Do you recognize them?" Sherlock inquired.

Raz squinted at the photos. "Not even sure it's a proper language."

Sherlock looked around once before saying lowly, "Two people have been murdered, Raz. Deciphering this is the key to finding out who killed them."

"What, and this is all you've got to go on?" Raz said with a shrug. "It's hardly much now, is it?"

"Are you going to help us or not?" Sherlock asked in slight annoyance.

Raz licked his lips before answering, "I'll ask around."

"Somebody must know something about it."

"OI!" someone suddenly barked from down the way. Harley jumped about a foot in the air in surprise, and she saw two uniformed officers rounding the corner and hurrying toward them. At first, she was frozen with panic. Oh, no. We're in trouble.

But then a hand grabbed hold of her wrist and yanked her into a sprint in the other direction. The force of it caused her to drop her notebook in the process, leaving it behind.

Ah! No!

Harley almost fought against the consulting detective, trying to plant her feet and wrench herself free to go back for it, but Sherlock kept a strong grip on her as he pulled her along through the back way. In the end, she gave up and just kept running, not looking back, the only goal being to get away from those cops now. They continued running even after they had gotten far enough away from the Gallery, pedestrians jumping out of their way as they raced past, his coat and her scarf flailing in the wind behind them.

Eventually they rounded a corner and slowed to a stop. Sherlock finally let her go as they leaned back against the wall, catching their breath. Once Sherlock had caught his, he started laughing, having found the chase rather thrilling. He looked down at Harley, who was still breathing rather heavily. He was about to say something, but then he noticed her twitching hands, and he realized what was missing — why she had tried to go back at first.

"Oh, your notebook. It…" he started, but trailed off; for she had held a hand up as she closed her eyes, taking a deep breath, like she was digging down deep for any amount of patience she had left.

Shaking her head, she took her backpack and reached in, pulling out another clean notebook and a pen. Luckily for him, she had better prepared herself for the worst earlier that morning. So she brought along spare supplies in case something like this happened. However, she still couldn't help but feel like she had lost a part of herself when she dropped that first book.

She tucked her pen behind her ear and stared levelly at Sherlock, daring him to say something demeaning.

Sherlock looked down at his phone, contemplating for a moment, before putting his phone in his pocket and looking back up at her. "Got your breath back?"

She nodded, her face still stoic.

"Back to Baker Street, then. We've got all the information we are able to get at the moment." With that, he started to lead her out of the alley they had taken residence in and out into the busy streets of London. Harley followed along behind, a little slower than usual. The adrenaline coursing through her body had died down, but her nerves still felt shot. Now that things have finally slowed down, she couldn't help but still feel like she was missing something, and it wasn't her last notebook.

Then she stopped abruptly and looked around as she discovered what was missing: her uncle. Everything had happened so fast and in a blur, she had forgotten that John wasn't with them anymore.

She ran up to Sherlock, who was about to hail a cab, and grabbed on his coat to get his attention. She flipped open her notebook and wrote down hastily:

Where's John?

Sherlock's gaze flickered at the direction they came running from, then back at her. He shrugged. "Don't know. He must've lost us on the way."

Harley raised her eyebrows. Just lost us? What if he had gotten caught? What if he couldn't find his way back?

Sherlock must've seen the confliction in her eyes, because a second later, he told her, "I wouldn't worry too much about it. He'll find his way back — he always does."

Harley was still a bit uncertain, but it was all she had to go on for now, and she nodded. After a moment of awkward silence, she wrote: So, this kind of thing happens often for you guys?

"Of course," he answered, just as a cab pulled up in front of them. Then he flashed her a grin. "But that just makes it more fun, doesn't it?"

She didn't respond that time, looking skyward before they got into the cab and drove off. She snuck a glance over at the detective once a few minutes into the silent ride, who was once again engrossed in his phone. It wasn't until his eyes snapped up at her a minute later did she finally look away, turning to gaze out her window at the buildings passing by.

She let out a tired breath, beginning to wonder herself what she had gotten herself into.

Oh, great. I'm starting to think like John now. How disturbing.


A/N- My dad makes a living by mixing chemicals together to create paint, and as an artist myself, I too dabble in paint, and how to make certain colors the way I want them. So yes, I do find pride in myself by knowing precisely what kind of paint Raz is talking about. *smugness overpowers*

Thank you to everyone who have favorited, followed, reviewed, or is just along for the ride so far! Love ya! CIAO! *leaves a me-shaped cloud of dust behind as I run off into the sunset*