AN: Same deal. Don't own either of the worlds, otherwise I'd be rich and quit my day job. Please leave comments if you can; anything you liked, didn't like, or just to say hi.

"In another moment down went Alice after it, never once considering how in the world she was to get out again."

-Lewis Carroll, Alice's Adventures in Wonderland

...

Follow the White Cat

...

Sherlock watched John's retreating form with a frown. Normally, he would be opposed to his partner running off right in the middle of a case. Not just in the middle, but right at the pinnacle. The work of two days, of searching around London and Surrey, chasing the most bizarre trail of clues that the consulting detective has ever encountered. Most of them, Sherlock had to admit he still had no answer to, though he would never admit this out loud. Sherlock was hoping that whatever or whoever was in this impossible house would have answers for him.

But John was gone now, shouting for a cab a few blocks away.

Why had I let him go?

Sherlock looked down in confusion at the gun in his hand. His mind was buzzing, strangely going around in loops, never coming to conclusive thoughts. Sherlock was definitely not comfortable with that. Something was messing with his head. Not just his senses, but his acute logical analysis of the situation. Try as he might, he couldn't formulate a plan or make a decent deduction. It almost resembled being drunk, if not for the clear vision and balance.

He could see John in the distance, getting in the cab now.

Go after him.

It was incredible, this single spark of an idea seemed so important. Suddenly, all that mattered was that Sherlock leave the doorstep of 122 Archer Street, and chase after John. Everything else in his mind became fuzzy, and Sherlock found himself ambling towards the gate of 122, towards John, away from the house.

The voice in his head kept repeating it: Go after him, it's incredibly important, you've just forgotten.

'Hang on, if it's so important, why have I forgotten?' A moment of clarity. John, remembering his anniversary (but it wasn't today) and running off. Him, Sherlock, almost running off too, for no reason whatsoever. What was this?

Sherlock looked back at the house, his eyes narrowed in suspicion. First, the illusion that defied geometrical reality. Now, odd impressions that overtook him and John, similar in nature, which caused them to flee. Something very intricate was going on; if Sherlock could only see the bigger picture. There was an answer, there had to be. Whatever it was, it almost certainly could be found in this house.

Sherlock began to amble up the path, back towards the door of the house. The compelling desire to run away was mounting on him every step, but now it was matched by his insatiable curiosity.

Go away, go to John.

Again, the voice was telling Sherlock, very plainly, that he needed to be elsewhere, and fast. However, another voice was also present, quieter, but more steadfast: 'How is he doing this to my head?'

At the door, Sherlock pocketed John's pistol, and considered his plan of entry. Picking the lock seemed instinctive, but now he reconsidered. The door, doorknob, and lock seemed simple enough. However, this man apparently rigged his house with mind-altering technology the nature of which Sherlock was completely unfamiliar with. Balance of probability suggested that the lock would not be simple at all, and picking it would waste precious time. Sherlock was still being bombarded by the overwhelming desire to run away, run anywhere, and he knew he would eventually succumb. Unless he got in quickly.

'Alternate entry: windows, obvious. Two windows are on the first floor, likely never opened, could be locked. Three windows on second floor, have probably been open before, light's on upstairs though, unwise to breach there, could be caught at disadvantage. First floor then, attempt window on the left, enter sitting room, stairs adjacent, entry possible, however perhaps it is wisest to SIMPLY GO HOME!'

Shaking his head of that last thought, Sherlock darted to the window on the left. Grooves and scratches on the frame suggest indeed it has been opened, but probably by former residents. The new resident however had not, and if Sherlock had to guess, the new resident might not even be aware that this window was here. This was a good choice then, unlikely there will be added locks. Sherlock quickly congratulated himself, and started prying open the panes.

After a few sharp jabs up and down, it gave. Sherlock heard one last booming suggestion that he must go immediately to John. Ignoring it, he climbed through into the dark landing.

Everything was upside down, there was a bottomless abyss underneath him, and he was falling, falling falling, forever and ever, but suddenly he was in Appledoor. Magnussen was laughing that sick laugh of his, flicking a kneeling Mycroft in the face. Magnussen turned, and began talking with an ugly accent.

"You should have known Sherlock, you should have figured it out. I thought you were a genius? Look how stupid you turned out to be! How simply delicious."

"I'm not stupid!" Sherlock yelled, anger and fear were paralyzing him, and he had no idea how old he was. He couldn't move, he couldn't do anything, except drown in his panic.

"Of course you are, even your brother thinks so. You are stupid, and childish, and now look what you've done? Everyone you love is in my pocket. I'm glad Sherlock, glad you've made this mistake. Glad you are such an idiot." Magnussen kept flicking the kneeling Mycroft. Suddenly, John Watson was there, walking up, and he knelt there too, at Magnussen's other side. Magnussen was now flicking John Watson and Mycroft Holmes in the eyes, in an off-beat rhythm. Mrs. Hudson, carrying a tray, hurried by in the background. She shot Sherlock a disapproving look, and was gone.

"Sherlock, look how very disappointed they are. They thought you were clever, they counted on you. You aren't clever though, are you? Now, I can do this to both of them, and it's all your fault. I can do this all day, forever and ever."Magnussen started flicking especially hard to accent his words. Oh god, he would be stuck here forever, and he would have to watch his failure play out over and over again. Sherlock was terrified. It felt like he had never been this scared in his life. Why was he so scared? He could barely think, all of his brain devoted to the panic now eating him up. He could barely think anything at all, except that somehow this was all very odd. Since when did Mrs. Hudson serve tea at Appledoor?

"They must be very angry with you. Are you angry with him, Mycroft? Disappointed?"

Mycroft turned to face Sherlock, flinching with every flick of that monster's finger. His face began to twist into a grimace. Mycroft now looked at Sherlock with such an expression of sadness and heart-wrenching sorrow, as had never been worn by the actual Mycroft ….all very odd...something...

"Hang on, Mycroft would never look like that, he doesn't show that much emotion, ever! No, not in a million years. This, this is all not real!" Everything came rushing back now, the case in Surrey, the dark-haired criminal named Potter, and the impossible house at 122 Archer Street. Magnussen was scowling, but everything was fading now, fading to mist. The last thing Sherlock saw was Mycroft wearing a triumphant smile.

"You figured it out, little brother."

Sherlock opened his eyes. Presumably, he had climbed through the window, as he was now standing in a dark sitting room, and his heart rate was way above normal. The panic was slowly dying now, but he could still feel it writhing inside him like something ugly and embarrassing that he wanted to squash.

Sherlock let a stream of choice words out, as he caught his breath.

Whatever that dream, or illusion, or drug-induced hallucination was, it was horrible. H.O.U.N.D. had nothing on that. It was so personal, so real, he could recall it easily, all the details sharp like a real memory. But what was it?! Taking a few shaky breaths, Sherlock decided to go on with his plan. The questions were piling up, and he needed answers. Sherlock really did hate not knowing.

He decided to take a quick survey of the situation. The overwhelming compulsion to run away seemed to have vanished, and he was returning to his senses. His brain was whirring into activity again.

'Sitting room, furnished carefully, very dusty. Creaks coming from second floor, casual, meandering, one man, he is unaware that I am here. A soft whistling as well, reminiscent of water vapor. Odd that he is unaware, I must have made noise opening the window. He's sure of himself, thinks no one could get through the strange and horrible security system, overconfident (don't blame him). Or, does not expect entry at street level. Hall is to the right, take stairs up, house has loud plumbing lots of white noise, manage to sneak up on him, can surprise him with weapon.'

A few more seconds to steady his breath, and Sherlock was creeping into the hallway, where a soft light was coming from the rooms upstairs. He sincerely hoped the stairs would be more or less normal.

2 Days Prior

"Why did it have to be Surrey suburbs? The most interesting case I've had all month, and it's in the most boring part of the country. These houses, do people actually live like this? How can anyone stand being identical to their neighbors?"

Sherlock could tell his friend and partner was getting annoyed at all his rantings (John is transparent). They've been driving for hardly an half an hour, and Sherlock managed to fill that whole time up complaining about suburban life.

"I think I would literally kill myself if I had to live here. In fact, let's put that down as theory number one for how these two kicked it. Elaborate suicide, spurred by the minutiae of the most dull life imaginable." Obviously, suicide was highly unlikely, but Sherlock thought he was being rather funny. John's face contorted a bit, and he looked away. Oh right, suicide seems to still be a sore subject with him.

They were nearly there now though, driving through the calm streets of Little Whinging (utterly ridiculous name), they turned on Magnolia Road, took another right and they were there on Privet Drive. It was eight in the morning, and they both had work to do. The police had all of number 4 sectioned off with tape, and all around Sherlock noticed curious neighbors peeking through their blinds, looking at the unusual activity on their street. Sherlock didn't blame them for looking. Everyone must be so bored here.

The chief, Nelson or Nilridge or something, met them at the tape to let them through.

"Glad you could make it Mr. Holmes, this one's a real mystery, impossible

murders, both of them. Got all of us just floundering for an explanation. Right this way, through here..."

It was a real mystery, and the murders were impossible, Sherlock thought after examining the scene, so the chief's initial assessment was correct. Man and woman, both nearing their 60's, found dead in their home. The man, in the living room, keeled over on the couch. No wound or obvious cause of death. First thing Sherlock would assume is heart attack, especially looking at the man's size. There was just one tiny detail that proved it couldn't be natural, and that was an expression of absolute horror frozen on his face.

The front door and back door are both locked, no signs of forced entry. These people liked their privacy, they had more than one lock. Nothing on the doors or windows was out of place, and Sherlock could spot out of place. Perhaps the killer was very careful.

The woman though, the woman was completely impossible. Same expression, lack of wounds consistent. But she was locked in her bathroom. There is no window there. The door had to be kicked in, as it was locked from the inside. So a woman died of fear, by herself in locked room? Sherlock began to examine the body on the bathroom tile. Her hands, he thought were very telling.

"Interesting..."he murmured.

She must have seen or heard something coming for her husband. She knew what it was, that there was danger, but the husband didn't realize it in time. She must have ran straight into the bathroom, locked herself in. Her palms had nail marks, from where she clenched her hand.

"The killer was in here with her. He stood right here," Sherlock placed himself at near the sink, "killed her, then seemingly vanished into thin air."

The chief tried to interrupt him.

"The door was locked, no one could have been here with her..."

"Which is why, you were right. This is a good mystery." Sherlock started glancing about, ruffling the things on the sink, soap, toothbrushes, a men's razor. A towel rack was hung on the wall, and he began to examine with his magnifying glass.

"The killer was close to 7 feet tall, she recognised him, or at least knew why he was here, didn't fight back, and he killed her. She was terrified, must have know it was coming. Look at the nail marks."

Sherlock rambled off all the other relevant information to the cop, who took it all down in his little notepad. Sherlock knew that what he was giving them wouldn't help them catch the culprit. There was something more to these murders, something that went much deeper. This older couple, the Dursleys, seemed to be the picture of normal, British family life. Their house was spotless, neat and very, very ordinary. Almost obsessively ordinary. So how is it that these two, who no doubt were very boring alive, could turn out to be such interesting corpses? What were Mr. and Mrs. Dursley hiding?

...

"You..." Sherlock hissed, careful to keep his voice low. "I should have known there was something off about you." Standing in front of the stairs, Sherlock was looking directly into a pair of yellow eyes. Sitting on a step half way up, looking for all the world like it belonged there, was the mangy, white cat from outside. It gave Sherlock an appraising look, and began to lick it's paw.

'Bit rude, luring me into a house booby trapped with deliriants, and then pretending like I don't exist.' Sherlock backtracked; cats weren't rude. Okay, back to logical deduction mode. This cat has somehow become important. Why?

The cat has been a stray most of it's life, evident by the coat, several small patches of hair missing. Probably lived in this neighborhood most of it's life, but, recently it has been taken in by an owner. Fur around neck is a little bent, someone tried to put a collar on it. Changed their mind, or maybe the cat didn't like it? The grey spots on the fur are dirt, but they're faint, so someone tried to give kitty a bath. The cat is also a bit fat for a stray, so someone's feeding it, although it doesn't live in their house, and apparently wanders about wherever it wants, and tricks unsuspecting detectives into psychedelic nightmare houses.

The cat came right up to Sherlock outside, before darting into the house, so it's not afraid of people. So all together, what does this give us?

'Somebody loves you, kitty.' The cat had stopped licking it's paw, and was staring at Sherlock. He got the strangest feeling that the cat was aware of what he was thinking. What business did a cat have, shooting him knowing looks like that?

The cat gave a loud meow, turned tail, and ran up the stairs out of sight. Sherlock began creeping up the stairs, slowly and noiselessly, once again following the white cat.