John went up the stairs to the flat, but came out to the landing again within seconds. "Mrs. Hudson!" John called urgently from the landing. "Where's Sherlock? We've had a break-in!"

"Why, I don't know, dear," she said, coming up. She peeked in the flat. "How do you know, John?" It was cluttered, as usual, obviously the home of two men who avoided housekeeping as much as possible.

"Well, look at it!" John said anxiously. "Everything's out of place! The skull is on the floor, my laptop is gone, and for some reason the chairs have switched positions. And, look – the music stand's been kicked over … argh, Sherlock's violin is missing!"

"Oh, I see," she said, not really seeing at all. "Maybe Sherlock took his violin?"

"Well, he never plays it anywhere but here … no, Mrs. Hudson, he only has one bow, and it's still there on the windowsill." He pointed. "Hmm. Maybe he took it for repair," he thought out loud, hopefully. "No ... he would have used the case," he said, pointing again. "Maybe they knew it was valuable. Where is he?" John asked again. "We need to tell him right away. This is urgent."

"Shouldn't we call the police?" Mrs. Hudson said, bemused. "Is the violin valuable?"

"Already done, first thing," John answered, holding up his mobile. "I have Lestrade on speed dial. And, obviously, it must be financially valuable to someone, or it wouldn't have been taken. But mostly it's valuable because it's essential to Sherlock to have it, that particular violin. He says it helps him to think."

"Can't you just call him?"

John pointed to Sherlock's mobile, alone on the kitchen table next to them, which was otherwise bare for once. "At least they missed that, although I can't imagine how," he said.

"Well, I'm sure I don't know how we could find him, then," she said, at a loss.

John was starting to wish Mrs. Hudson would go back downstairs. You're not helping, he thought impatiently. I know you mean well. She prattled on, something about needing to get better security locks, while he walked through the rest of the flat, checking for anything else noticeably wrong. They'd have to inventory smaller things and papers later, of course, but that would take precious time. He tried to look with Sherlock's eyes … he'd want data, and there might not be time for him to return to the flat to see for himself.

As John came into the bedroom, he saw that Sherlock's laptop was on the bed, turned on. Surprising they didn't take that, John thought. They must just have wanted the violin… no, they took my laptop, so why not this one? … maybe my return scared them off … or maybe they never came into the bedroom ... Theories started to form in his head. Sherlock would surely shoot each one down as soon as mentioned them, but it didn't hurt to consider the possibilities. Mrs. Hudson was still talking as John returned to the main room, frowning thoughtfully, but she stopped when Lestrade suddenly strode in.

"I don't normally respond to break-in calls, but I was just a couple of streets away when it came over the radio," he explained. He looked around. "So, problem in one of the bedrooms, John?"

"No, here," John said, indicating the flat with a broad sweep of his hand. Lestrade looked again, and then turned back to John. "You've had burglars switch your chairs and tip over Sherlock's music stand?"

"No, Greg," John said irritably, as the inspector walked through the kitchen and poked his head in Sherlock's bedroom. It doesn't look like he slept well last night, John thought. I guess he's having a slow day. "Sherlock's violin's been taken, and so has the laptop I always keep in the main room. And a bunch of little things not right, papers shifted, the skull on the floor, the harpoon in the wrong corner. Couch pillows on the chairs. Someone, or several people, searched this place pretty thoroughly, but he or she didn't want it noticed immediately."

Lestrade turned to him, annoyed. "John," he said sternly, "I can't come running over here every time one of you decides to shift the furniture around without asking the other or you mislay something under your laundry. Where's Sherlock? I'm sure he can explain things to your satisfaction."

"He's not here," Mrs. Hudson said. "Maybe he's just out on an errand." You mean on a case, John thought. I'm the one that usually gets sent out for errands.

Lestrade said pointedly, "Well, in future, if a coffee mug goes missing, I'd much appreciate it if you called your own in-house consulting detective first, before you bring the police in on the case."

John silently held up his phone, to indicate that the one resting on the table between them was not his. Lestrade kept talking, though. "Right you are, John, I assume you have a speed dial key for Sherlock." Disgusted, he let himself out, making more noise going down the stairs than was necessary. John stared after him.

Right, then … how can I contact Sherlock? He's not here, didn't take his phone … Mrs. Hudson interrupted his thoughts. "Did he leave a message, maybe?"

"No, Mrs. Hudson," John said. He just barely caught himself from rolling his eyes. "I checked that before I called the police." He wagged his mobile at her before returning it to his pocket.

Hush, now, please, he wanted to say, but he was restrained by politeness. He went back to his train of thought. Message … "Oh, wait, message, that's actually a very good idea," he said, suddenly. He went back to the bedroom and returned with Sherlock's laptop, already thumbing the trackpad.

"You're not going to pry into his computer, are you?" Mrs. Hudson fussed.

"Well, he's always getting into mine, but no. I'm just looking to see if there's anything here that can tell me where he might have gone. And there we go," John replied, mildly triumphant, shutting the laptop and jumping back up again. "He's at the library. He must have left about fifteen minutes ago." He shrugged into his jacket. Maybe it's good she didn't shut up after all. "Thanks for the idea about the message."

"However can you tell where he is?" she asked, astonished. "Did he leave a message?"

I don't have time for this, he thought. I need to get Sherlock on this, right now. But he answered her, momentarily overcome by a touch of smugness. This was serious and time was critical, he knew that, but he was on a roll.

"No, Mrs. Hudson. That's his email account up on the laptop – none of today's read but the first, and that was from the library. The subject line says his patron account is about to be suspended for overdue materials and unpaid fines. The library books he borrowed are gone. I hardly think the burglars took them, unless they're interested in high-energy particle physics."

"The library closes in five minutes," he added, checking his watch. "If I hurry I might be able to catch him before he goes somewhere else, and the thieves won't be too far ahead." There, satisfied? He tried to step around her to leave, but she put an arm on his. He stopped, resisting the urge to sigh deeply.

"That's incredible," she said. He stopped, considering. Well, okay, maybe I wouldn't have thought to do exactly that a year ago, but it wasn't exactly rocket science, and I suppose it's good thing, to not be the same person I was a year ago. "Thanks," he said simply, already trying to figure out how he would break the news to Sherlock that his violin was gone.

"You clever boys," she said fondly. "I don't understand either of you, but I'm so glad to have you here. Good luck, dear."

As he trotted down the street to the library, John smiled wanly to think of Mrs. Hudson, lumping him in with Sherlock Holmes for cleverness. If only. No, one Sherlock in the world was far more than sufficient.

He spotted Sherlock on a wide concrete bench outside of the library, his dark wool coat tossed carelessly beside him, apparently enjoying the fine weather. Gratified that he had been right, John approached, slightly out of breath. "Sherlock," he began, "There's been a break-in at the flat, only minutes ago. We might still be able to catch them."

Sherlock looked mildly interested. "Really? What's been taken?"

John paused. This is going to really upset him, he thought. He loves that thing. "I'm sorry to say that your violin is missing," he said seriously.

Sherlock looked back at him, impassive. "Anything else?"

Nerves of steel, when something - or someone - he cares about is in danger."Ah, yeah, my new laptop, damn it. Probably more, but I haven't done a thorough check."

In answer, Sherlock smiled slightly and lifted his coat to reveal a shoulder bag. He handed it to John. "You can thank me later, when you see how much faster it runs now," he said. "I've cleaned off the hard drive for you, and set up permanent controls to prevent connections with dodgy web sites."

"Sherlock," John said suspiciously, automatically taking the bag. He was momentarily distracted from his mission. "What did you do?"

"Set it up so that porn sites are no longer accessible, and deleted your hoard of virus-laden images that you'd downloaded."

John closed his eyes and sighed. "Sherlock, that wasn't a hoard, that was a collection. They were artistic." Sherlock replied to this assertion with a wordless, level look. Then he flipped the tail of his draped coat back up onto the seat. He reached under the bench to pull out the familiar shape it had concealed, wrapped in a light quilt and twine.

"Oh, thank goodness, I thought the thieves had taken that," John said. Sherlock put on his coat, and together they began walking toward the flat. Keeping up with Sherlock's long strides, John nearly had to jog again.

"You've called the police?"

"Yes, and Lestrade showed up."

"But he wasn't willing to help."

"No. He wasn't." How like Sherlock, to see things so clearly, even when he hasn't been there to see the evidence himself yet.

"It didn't occur to you that I might have had the violin?" Sherlock asked, curious.

"Well, yes, but then I saw that the case and the bow were still there."

"Why didn't you just call me?"

"You left your mobile in the kitchen, out in plain sight. Not that either Mrs. Hudson or Lestrade noticed; they were just about looking at it when they each suggested I call you."

"Ah. So I seem to have done," Sherlock said, rummaging in his empty pockets. "So how did you know I was at the library?"

"Mrs. Hudson," John said, sighing, "means well, and I'm very fond of her, but she's just not the brightest bulb in the box, if you know what I mean. I saw one email subject line on your laptop screen, and the books gone, and she thought I was some sort of genius for figuring out you probably had gone down to the library no more than fifteen minutes earlier."

"Fifteen minutes?"

"Because the screen saver that requires a passcode hadn't come on yet," John explained. Sherlock's lips curled into a small smile.

They arrived at their door. Just before they went in, Sherlock told John mildly, "Mrs. Hudson is sharper than she looks. When she has reason, she can appear to be quite helpless, but nothing could be farther from the truth." As they entered the hallway, the woman herself came down the stairs.

"I've tidied up a bit, boys. Have a nice evening!" she twittered.

Sherlock gave her a brief but surprisingly tender embrace as she went by. "Thank you, Mrs. Hudson." She disappeared into her own flat.

Looking at her closing door, John gave a quiet but exasperated sigh. "And destroyed what evidence there might have been on the crime scene, thanks a lot."

"As I have sometimes seen you inadvertently do," Sherlock said calmly, as they entered their flat. He took a seat in his chair. John noticed that it was back to its usual place. In fact, now that he looked, every single thing that had been out of place was back, even the things he hadn't specifically pointed out to Mrs. Hudson … and a few things that he hadn't noticed himself had been wrong before. The Union Jack pillow had been on the couch instead of the chair, and now it's back. How could I have missed that? Sherlock, enjoying himself, watched realization dawn on John's face. John turned to him.

"I've missed something, haven't I," he said.

"No, actually I think you covered everything fairly well," Sherlock said. "Well done."

Well done? "So this was a test." John said flatly. "And Mrs. Hudson was in on it."

Sherlock was clearly amused. "As I said. Sharper than she lets on."

"And Lestrade. Coming from just a couple of streets away, what a coincidence."

"Not exactly. I arranged for an incident to occur nearby, to draw him to the neighborhood. After he received the call I knew you would make, I knew I could just count on him to be himself."

"Why?" John said, angrily. "Just to get your jollies, watching good old John trot around, all concerned for your precious violin and upset about a break-in?"

"No. It was an experiment, to see how much you've progressed in observation and deduction skills since we've been together. Obviously farther than I had given you credit for."

John looked back at him. Then, he couldn't help but chuckle. "OK, that is the most backhanded compliment I think I have ever received. Sherlock Holmes, telling me I'm not as dumb as he thought. That's saying a lot, too, coming from you. I'm honored … I think. In retrospect, this really wasn't much of a challenge, even I see that."

"I wanted a clear result in the experiment. And also," Sherlock said, "something more."

John thought a moment. "You wanted to see which I was more concerned about, your violin or my new laptop. I guess I passed that part of your little test too. You know, Sherlock, if you want to know your friends better and see how well they like you, you could just talk to them."

Sherlock looked at him with interest. "Actually, John, I didn't set that part up on purpose. I just took the two most valuable things in the flat, and it just so happened that one belonged to each of us. But an interesting result nonetheless, now that you point it out," Sherlock said. "However, the main point of this, let's call it a 'training exercise', was something to help my only friend understand me better."

John looked at him questioningly.

"You've just had a half-hour's taste of what it's like to be me."