When Kim found the place it was empty.

She had sworn to herself that once she found it she'd never, ever leave, would never turn her back on it or pretend it hadn't happened, would never go home and pick up a fork or turn on the television or open a window like nothing had happened, but that's exactly what she did. Because when she'd made those promises she'd been expecting - not Narnia, Narnia was too circumscribed, Narnia did not grant Narnian green cards and invite you to stay for the rest of your life, but she'd been expecting Fairyland, or a Shadow Realm, and she would have settled on some days for a more atmospheric than practical Hell. She could do worse than to fall into a YA romance protagonist role with a demon cozying up to her, intrigued by her mortal charms.

But there was nothing there.

It took her four days, fuming about it to herself, snapping at her cat, crying into her Häagen-Dazs, before she went back to the side door behind the empty crepe place that no one had filled with anything since it closed six years back.

Just to see if it was still there, not to go in. It was not a place she could live. There was nothing there; her flashlight met walls just forty feet away past the threshold and not even a mote of dust drifted through the beam.

The crepe place was about twenty feet wide, its kitchen reached all the way to the back and this door should have been access from there to the trash alley, and beyond this building, its neighbor the bike shop did not extend that far back. The room couldn't exist. It was indisputably magic.

It was a lightless, windowless hallway with concrete floors and sides. She could use it as a glorified space-warping storage unit, she supposed.

She glared at it, willing it to turn into a verdant realm of adventure. For something to walk through the wall or drop through the ceiling, introduce itself, show her how to do it too so she could navigate its world.

It was a lightless, windowless hallway. Concrete.

She ground her teeth and stepped into it. Ignoring it hadn't helped make the whole thing any less unfair.

It at least felt something like passing through a magic portal ought to, like a curtain was brushing over her skin. The air was thin. The floor was hard, and cold enough to notice through her shoes.

There was still nothing there, no invisible universe waiting for her to take her first step into it before unveiling its splendor.

She went all the way to the far wall and laid her hand on it. It was cold, but warmed up as she stubbornly left her palm there, trying to derive some enjoyment from being in contact with literal magic and finding that there was none.

Kim turned off the flashlight and let her eyes adjust to the light there wasn't. Nothing had been waiting for that, either.

She could leave this place, open more doors, find a better one. If there was one, there might be more. Some might lead to proper fantasy lands. Populated, bright places where you bought witches' magic charms with gold coins and this highly space-efficient closet was something you saw every Tuesday.

She had opened a lot of doors in her life and this was the first magic one.

She might never find another.

Kim set down the flashlight on the floor. When she checked a moment later, prodding it with her foot, it was still there, having neither been stolen by goblins nor turned insubstantial by mysterious forces. There was just really actually nothing here, and she needed to stop letting her heart rate jump every time she breathed in case that was the right number of breaths to take to earn her ticket.

She waited in case accepting that there was nothing here was something's cue to surprise her.

She gave up on waiting, just for half a second. That didn't work either.

Why couldn't it have been a magic necklace in an inherited jewelry box, or a tunnel to a cave full of dragons, or -

Why was it a featureless corridor? Unnaturally clean, and not even quite that. It had been but she'd left footprints, tracked bits of mud in with her. This was the only magic she'd ever found in her whole life and she'd tracked mud into it and she couldn't even be horrified at herself about it because the magic was so pathetic.

Maybe the relative thinness of the air would power some kind of perpetual motion machine if she knew what to set up on either side of the threshold. That would be the wrong genre, but sort of okay. If she knew how to build a perpetual motion machine, or who to ask.

Kim sat in the corridor, shivering as the nonmagical but still considerable cold of the place sank into her. She sang songs. She recited the Fibonacci sequence. She took cellphone pictures of the place, with and without flash. She ran her fingers along all the edges of the room, between the walls, at the boundaries of the floor. Wasn't tall enough to reach the ceiling. Hadn't brought a stepladder and was going to feel really stupid if there was a hidden trap door up there offering passage to where she really wanted to be.

She left. (She checked her watch against a clock on a nearby bank's marquee. Time had not dilated.) She tried the stepladder the next day. Nothing in the ceiling.

After that she didn't come back for a few weeks.

Kim had read once about a man whose wife had died because she couldn't get to a doctor fast enough. The only route had been around the mountains. He'd taken a chisel, and he'd gone out, and he'd started hacking away at those mountains. When he was done, there was a road straight to the town with the hospital.

His wife was already dead and nothing he did could save her.

But the next time something like it happened, there was a way to get to help, even though it took him twenty-two years of daily work with inadequate tools.

Kim went to the hardware store and bought an extension cord and hearing protection and everything else the guy who worked there recommended for her edited explanation of her purpose, and she rented a jackhammer.

Before she tried it she checked the soundproofing in the room, leaving her phone blasting the most obnoxious metal she could find streaming, the door propped wide open. It wasn't audible at all from past the threshold. Then she plugged everything in and put on earmuffs and took the business end of the jackhammer to one of the long walls.

Progress was slow. She made a little hole, then moved over and made another little hole, and so on and so forth. She did not get much done. But she'd proven the wall was destructible, and she wasn't breaking through to the non-space-warped outside, either. She returned the rental and bought a jackhammer of her own. She'd expected them to be more expensive.

She chipped away at the wall every day for a week and a half. The room that had seemed so small and disappointing was much bigger when trying to renovate it. She gradually pockmarked the whole smooth cold wall, and learned to change the oil in her jackhammer, and then started hammering away at the bits between the holes. It felt bigger than it had but it wasn't big enough. It needed to be cavernous.

When she came back on the eleventh day, the wall was smooth again, and she couldn't think how to feel about that - it was reacting magically to what she was doing, it wasn't a perfectly static room, that was at least a response, a magic property other than the pressure differential and the warped space, but it was reverting back to its original size and shape, it wasn't going to be possible to fix it so the next person who needed to find a fantasy world at least got to explore a huge cave full of - she hadn't decided but at least something like the world's biggest diorama, something they could pretend fairies lived in -

The hall was wider.

It had smoothed itself out to the depth of the holes she'd made in it.

Kim burst into tears and picked up her jackhammer and got back to carving out her cavern.

The place got a little quicker about reacting to her changes over time. She could get an inch or two out of the walls in all directions with one hole in each, and they'd slightly curve the new editions depending on where she placed the holes - she was going for concave and generally drilled in the middles, but didn't want it to look too artificial so she mixed it up sometimes. It didn't look very impressive day to day. But if she did it every afternoon for twenty-two years, like she was chiseling a road through a mountain, then even if it didn't get any faster or more malleable she'd have a cavern almost fifteen hundred feet across.

She marked out foot-wide half-ellipses in chalk, starting door width and expanding concentrically from there until she didn't have enough width, and drilled into those, a little deeper into each progressive one and the space beyond too. When she came back, the room hadn't figured it out; she drew another one, hammered a few more holes, and came back the next day to stairs as smooth as they would have been if a river had been running over them for centuries.

She added another stair every couple of days, since she wanted them broad and shallow. She hadn't decided yet how deep she wanted to go, but she thought it should be at least double the height of a normal flight of stairs, which would mean at least a hundred of them given how little depth each added.

She started experimenting, after a while, with what other suggestions the room would eventually get the hang of. She hauled a hose behind the building, found a spigot sticking out of the back of a bagel place, and in what was probably a form of water theft ran the hose down the stairs, as soon as they were steep enough and deep enough for this to make a pleasing trickle and not immediately flood the place. She didn't run it too long; she didn't want to make a huge puddle at the bottom. Just a small stream for a few minutes. It didn't get the idea right away. She waited for it to dry, storing her hose outside the room in the alley and assuming no one went out and decided to look for a garden hose to steal, then tried again. It finally figured out what she wanted after the third try: a perpetual flow of water down the stairs, not wide enough to make them all wet and slippery but plenty to make a pleasant burbling sound. The water disappeared at the bottom of the slope, which deepened every day.

She found a little piece of nice bluish granite at a gift shop and laid it on the steps, then propped it up against the wall. When she came back, there were six of them lying around. She sighed and hauled five of them out, then tried dragging the flat of the granite along the walls and the steps and removing it altogether. The next day she'd successfully turned all the surfaces to granite, which made them harder to jackhammer but she was now barely scratching each surface before moving on and expecting the place to get the hint.

She caught fireflies, in firefly season, and released a jarful, and when she came back there were more of them, and thereafter their number scaled with the gradually expanding volume of the cavern. She bought a bioluminescent plant online and placed it, and then there were more, in their own little loose piles of dirt she could shove to suitable locations; once she'd indicated where they belonged the cave embedded them deeper, grew them bigger and closer.

If she'd found this place, she would not have been disappointed right away. She would have been later - but it would have taken her longer.

The stairs grew into broader shallow terraces. The walls receded faster and faster, four and five inches disappearing from each side in a day. She added moss for texture, crickets for sound. She did not know how to catch an owl or a bat, but if any appeared conveniently to her she'd know what to do with them. She got a stepladder, perched it precariously across two steps near the door, and held up a dripping-wet cone shaped rock to the ceiling, and came back to a very satisfying array of stalactites. She got a little collection of semiprecious gem chips, scattered them like glitter down the stairs, and came back to jewels embedded in all the stone.

She decided to stop expanding the cavern as a whole once it was fifty feet wide. She made tunnels, drew them into the wall in chalk to clarify how they ought to be shaped and directed passages this way and that, branching and twisting. She planned the whole thing out on paper, but the room was not yet quite savvy enough to pick up on what the floorplan meant. She had to scrub out its attempts at printing the map on the wall. That would spoil the mystery for whoever came next.

She put in dangling orchids. She bought a salt lamp; the ones the cave created, as she'd hoped, did not need batteries, and just glowed through lovely colored crystals sconced on the walls.

Kim still showed up to work, still even paid rent on her apartment - she could have turned the cave into a home but that wasn't what it was meant for. But her passion was the dig, the construction. She slept at home and worked at work and the rest of the time she was shopping for and crafting for and rearranging the cave. Her paycheck, after rent, went mostly to supplies to donate to her project. She'd convinced the cave to generate meals for her by showing it a compilation video of Star Trek replicators and then drawing a little alcove on the wall, and chipping away the unthematic sci-fi components and repeating the video as necessary until it worked plain, just an alcove that would appear any food she named. She did something similar to make a garbage disposal chute.

Months disappeared into the cave, then years. It glittered. She'd brought in a fog machine. She'd volunteered long enough at an animal rescue to get access to a little bat for the place and it had bats. There was a dollhouse village that took an entire summer all by itself to get just right.

When she'd been working on the cave for twenty-two years, it was a maze the size of a small town, three dimensions of pockets and tunnels both broad and cramped. She knew the place like the back of her hand, but to someone discovering it for the first time it would be dizzying, exciting, surprises around every corner. There were stained-glass windows to nowhere, mushrooms the size of dogs, a roomful of hundreds of hourglasses set into the wall turning themselves over and over, a chessboard in ivory and ebony inlaid into floors, music that chimed and plinked to itself in sparse tunes that sometimes piled up into glorious harmonies, tiny nooks with the leftovers of imaginary civilizations.

It was beautiful.

It was a dead end.

If someone - Kim imagined a middle-schooler with untied sneakers and a backpack full of algebra homework - if someone found it now, they'd have a lot to see, a lot of magic to investigate. Something cool to show their friends. Years' worth of escapist entertainment before they realized the secret of the place, and Kim knew that was valuable as far as it went. But it just wasn't a fantasy kingdom like that kid deserved to find. That kid might have a good time adding to her work once they realized it had all been artificial, but that wasn't what she was trying to do, she wasn't trying to leave a truncated version of the real thing.

There was nobody in there but grayscale bats and rainbow fireflies. Singing crickets and giant moths. Snakes and mice and sparrows, which she'd coaxed into fantastic patterns of scale and fur and feather, but animals.

She went to her dollhouse village. She'd modified the original dollhouse a lot - taken out the stairs, put doors on the outside walls of the second and third stories and a door in the roof. She'd taken the backs off the tiny chairs. She'd painted everything, made little tweaks to all the architectural detailing, till the cave figured out the color palette she wanted and the style and produced more houses like that. It was a fairy village.

And she found those pictures of fairies that had fooled Sir Arthur Conan Doyle, and a lot of fantasy art from the internet, and a coffee table book full of paintings of fairies, and left it all there atop the tower of civic buildings in the center of town, and held her breath, and went out of her cave.

She didn't go back to retrieve the phone or the book or the photos right away. She had the idea of never going back at all, of letting the kid find it, letting the kid really be the first person to meet them. But she couldn't resist. She told herself that she wasn't sure it would work on the first try. She'd never attempted something quite like this before. And the things she'd left behind would be belief-breaking clues that someone had architected the place, that there hadn't all along just been cave fairies living in a cave system at the back of a crepe restaurant.

She went back, and she didn't meet the fairies.

They were there. But they were sleeping. She tiptoed through their village, held her breath and tried not to cry when she saw their little faces through their windows. It was perfect. The kid with the untied shoes could be the first person they'd ever met, but she got to see them.

She took her things and blew the fairy village a kiss and went out of the fantasy kingdom.

She had another twenty-two years in her. Maybe she could find another door.

Next time, she thought she'd do one with unicorns.