Unseeing Distance

I.

The body was wrong.

Not wrong in the way that murder makes a body wrong — the slack mouth, the stopped-clock quality of a face no longer running. Nessa Tiernan had seen plenty of that. Eight years with the Garda Síochána will furnish you with a catalog of the dead and their postures, and she had long since stopped being surprised by the positions people chose for dying. This body was wrong in a different register. Wrong the way a word is wrong when it appears in the wrong language in the middle of a sentence.

The woman lay on her back in the service alley behind Aughrim Street, between the recycling bins and a stack of collapsed cardboard boxes. Stoneybatter, northwest Dublin. Nessa’s patch. She knew these streets the way you know the layout of a kitchen where you’ve cooked for years — not by memory but by muscle, the body navigating without consulting the mind. She had walked this particular alley last Tuesday. She was almost certain.

The dead woman’s coat was the problem. Or not the coat itself — a heavy wool thing, dark green, double-breasted, well-made — but the label inside the collar. Nessa had checked it while pulling the coat back to look for visible injuries, and the label read SEOIGHE & DAUGHTERS, MANOR STREET, in a typeface she didn’t recognize. There was no Seoighe & Daughters on Manor Street. There was Tesco Metro and the credit union and the Filipino grocery and the bookmakers. She had walked Manor Street this morning.

The woman’s shoes were handmade. Her bag — canvas, stained, carrying the smell of woodsmoke — contained a purse with coins Nessa couldn’t identify. Not euro. Not sterling. Round, heavy, stamped with something that looked like a heron standing in water. Her phone was a model Nessa had never seen: thick, with a slide-out keyboard and an interface in Irish that used words Nessa didn’t know, though she’d gotten her Leaving Cert through Irish.

“Superintendent?” That was Dáithí, the scene tech, looking at her with the expectant patience of someone waiting for her to confirm what he already suspected.

“Document everything,” she said. “Especially the personal effects. Photograph the coins. And get someone from — ” She paused. From where? Forensic accounting? The Mint? “Get someone who can identify the currency.”

“Right so.” Dáithí didn’t ask the obvious question. He was good that way.

Nessa stood and looked at the alley again. The walls were right — she recognized the graffiti tag on the left wall, the cracked rendering on the right. The bins were right. The pavement was right. Only the body didn’t fit. It had been placed here, or it had arrived here, from somewhere that shared this alley’s geography but not its reality.

She was aware she was thinking something she would not write in her report.

II.

The coins were the thread she pulled.

She took two of them to Pearse Street, to a numismatist she’d used once on a counterfeiting case. He turned them in his fingers for a long time, held them under a loupe, tapped them against the countertop.

“They’re not replicas,” he said. “The minting is genuine — industrial, consistent, not hand-struck. The metal composition is standard for coinage. Copper-nickel. The problem is that this denomination doesn’t exist.”

“What denomination is it?”

“If I had to guess — and I’m guessing — it’s a ten-punt piece. Decimalised punt. Except the punt went out of circulation in 2002 and this coin is stamped 2024. And punt coins never came in ten-denomination. And they didn’t have a heron. They had a salmon.”

“A heron.”

“Standing in water. Beautifully done, actually. Reminds me of the old Hairy Penny.”

Nessa took the coins back. She sat in her car on Pearse Street with the engine off, turning them in her own fingers, feeling their weight. She had a dead woman with no identity in any system — no passport match, no driver’s license, no PPS number. A woman whose clothes came from shops that didn’t exist on streets where Nessa had walked that morning. A woman whose money came from an Ireland that used a currency it had never issued.

She drove back to Stoneybatter. Parked on Oxmantown Road, where a skip full of demolished bathroom fittings sat outside a house being gutted for renovation. Three doors down, the Kavanagh place was already finished — skylight, Farrow and Ball on the door, an architect’s card still in the window. The neighborhood was eating itself and replacing what it swallowed with something more expensive. Nessa noticed this the way you notice weather: constantly, without thinking it was anything you could change.

She walked Manor Street looking for Seoighe & Daughters and found the Tesco and the credit union and the bookmakers in their accustomed positions. She walked it again. The October light did that Dublin trick where it made everything look both washed out and hyper-specific, every brick edge sharp, the sky a uniform pale nothing that refused to commit to either rain or clearing.

On her third pass, she noticed the door.

It was between the credit union and the Filipino grocery — a space she would have sworn was a solid wall. Not a hidden door, not a door painted over. A door that she had apparently been looking at for years without registering. Wooden, painted a dark red that had weathered to the colour of dried blood. A brass handle, green with verdigris. No number. No letterbox.

Nessa stood in front of it. People moved around her on the pavement, none of them glancing at the door. She watched a woman with a pushchair navigate past it without looking, adjusting her path as if the door occupied physical space — which it did — but not perceptual space. A man talking on his phone stepped wide of it, his feet describing a detour his eyes refused to acknowledge.

She reached for the handle. The brass was cold in a way that had nothing to do with the weather. She turned it and the door opened onto a shop interior that smelled of lanolin and wood shavings and something else — something herbal, astringent, like a plant she couldn’t name.

SEOIGHE & DAUGHTERS, read the sign above the interior counter, in that same typeface from the coat label.

III.

She should have called it in. She should have backed out of the door, returned to the station, written a report that she knew would read like the onset of psychosis, and let someone else — Threshold, probably, though she was fuzzy on what Threshold actually was, just a name that appeared in interoffice memos she’d learned not to look at too closely — handle whatever this was.

Instead she bought a scarf.

It was instinct, or cowardice, or some detective’s reflex that said: don’t announce yourself, observe first. The woman behind the counter was somewhere in her sixties, with cropped grey hair and hands that moved with the confidence of someone who’d been measuring and cutting fabric for decades. The shop was full of coats, scarves, gloves — all handmade, all in that same heavy wool. The dead woman’s coat had come from here.

“Caoga punt,” the woman said, and Nessa understood her — fifty punt — though the price made no sense in any economy she knew. She put the dead woman’s coins on the counter and the woman took two of them without comment and gave her change in smaller coins stamped with birds Nessa didn’t recognize.

“Grand day,” Nessa said.

“It is.”

She left the shop. The door opened onto Manor Street, which was Manor Street but was also not Manor Street. The buildings were the same Georgian terraces, the same brick, the same slate roofs. But the satellite dishes were gone. The cafés were gone. In their place: a greengrocer with crates of produce she couldn’t fully identify, things that were shaped like turnips but the wrong colour; a blacksmith — an actual blacksmith, she could hear the hammer striking something that rang too high and too long; a pub called An Corr Éisc with an elaborate hand-painted sign showing a heron.

The cranes over Grangegorman were gone. In their place, trees. An entire canopy of them, dense and dark, starting where the development site should have been and extending further than she could see. The trees moved in a wind she could not feel on the street. Their leaves were a green so deep it was almost black, and something in them produced a faint light — not phosphorescent exactly, but present, a luminosity that seemed to come from the wood itself rather than from any external source.

People moved through these streets with the unselfconscious ease of people in their own neighborhood. They wore heavy clothes — wool, leather, canvas. Some carried lanterns that weren’t lit but still gave off a pale glow. One woman walked a dog the size of a small pony, its coat a deep indigo that Nessa’s eyes refused to settle on, as if the colour existed at a frequency her optic nerves weren’t calibrated for.

No one looked at Nessa. She walked for an hour, learning the neighborhood’s shape, and no one spoke to her except to say excuse me when she blocked the narrow pavement. She was wearing her work clothes — dark trousers, grey blazer, flat boots — and she stood out the way a tourist stands out: not by appearance exactly, but by the quality of her attention. Everything she looked at, she looked at too long.

She found the dead woman’s flat by smell. Woodsmoke, the same woodsmoke that had clung to the canvas bag. A door on Kirwan Street — a street that in her Stoneybatter was called Kirwan Street too, but contained different buildings, or the same buildings differently used. Where her Kirwan Street had the new apartment block with the underground parking, this one had a terrace of low stone houses, each with a door painted a different colour. The dead woman’s door was blue. It was unlocked.

Inside: a one-bedroom flat, clean, sparse, lived-in. Books in Irish on shelves made from rough planking. A bed with a heavy quilt stitched in a pattern of herons. A kitchen table with a mug still on it, tea cold and dark. Nessa picked up the mug and held it. She was holding someone else’s morning — the last morning, the one that had ended in an alley with collapsed cardboard boxes and the wrong kind of coins in a purse that smelled of woodsmoke.

On the kitchen table, beside the mug, a photograph. Two women standing in front of An Corr Éisc, arms around each other, laughing. One of them was the dead woman. The other looked — Nessa set the photograph down and stepped back.

The other woman looked like Nessa.

Not exactly. The jaw was different, the hair darker, the smile more open than any smile Nessa had produced in years. But the resemblance was there, undeniable, in the way the woman held her shoulders, the tilt of her head, the particular stubbornness of the mouth. It was the resemblance of a word translated into another language — different in every specific way, identical in what it meant.

Nessa sat at the dead woman’s kitchen table and did not touch anything else for a long time.

IV.

Her name had been Sorcha Ní Bhriain. Nessa learned this over the following days, which she spent moving between the two versions of Stoneybatter with increasing ease and decreasing comfort. The door on Manor Street was not the only crossing point — there were others, and she found them the way you find a loose thread in a garment: once you started pulling, the whole structure revealed its seams. A gate in the Phoenix Park that opened onto a park that had no zoo but did have standing stones. A basement stairway off Brunswick Street North that descended into the wrong building. A stretch of the Liffey boardwalk where, if you walked with your eyes half-closed, the Ha’penny Bridge had a second span that arced toward a bank that didn’t exist on your side.

In her Stoneybatter, Nessa filed reports, attended briefings, told Dáithí the coins were a dead end. She drank bad coffee in the station kitchen and listened to her colleagues discuss cases that stayed inside the lines of a single geography. She was getting good at this — at conducting two lives along parallel tracks, one visible and one hidden, each requiring its own set of habits.

In Sorcha’s Stoneybatter — she had started thinking of it that way, possessively, which was the first warning sign — she inhabited the dead woman’s life like a hand fitting into a glove that was almost but not quite her size. She wore Sorcha’s coat. She drank tea from Sorcha’s blue mug. She spoke to Sorcha’s neighbours, who assumed she was Sorcha, because the resemblance was close enough, and people see what they expect to see. An older man on Kirwan Street asked her how the research was going and she said “slowly” and he nodded as if this confirmed something he already believed.

This was the thing about overlapping neighborhoods: perception was the architecture. The residents of Nessa’s Stoneybatter did not see the other version because they had been trained not to. Not by any conspiracy, not by any enforcement body, but by the accumulated weight of normality. You walked past the red door on Manor Street because you had always walked past it. Your brain filed it as wall because door to another reality was not a category it kept. The brain is a miser. It will not maintain a category without evidence, and the unseeing kept the evidence out of sight.

The residents of Sorcha’s Stoneybatter did the same thing in reverse. They did not see the satellite dishes, the cafés, the cranes. To them, Nessa’s version was the ghost, the overlay, the thing the eye slid off. Two neighborhoods, two populations, two economies, two versions of weather — Nessa had begun to notice that Sorcha’s Stoneybatter was colder, its rain heavier, its light that deep amber where hers was grey — occupying the same grid of streets with a mutual indifference enforced not by law but by the inability to imagine an alternative.

Between the two, keeping the separation intact, was Threshold.

Nessa had encountered Threshold exactly once in her career — a case she’d been pulled off without explanation, a file that had disappeared from the system, a quiet conversation with her superintendent that had the texture of a threat delivered as career advice. There are things that are handled at a different level, Nessa. Best not to inquire. She had not inquired. She had done what she was good at: she had unseened.

But Sorcha Ní Bhriain had not been good at unseeing. Sorcha had been a scholar — the books in her flat suggested someone who studied the boundary itself, who mapped the places where the two neighborhoods bled into each other. Her notes, which Nessa found in a drawer beneath a false bottom, were written in a cramped, furious hand, in Irish so dense and technical that Nessa could only understand fragments.

The membrane is thinning. Has been thinning for years. They know this. The question is whether Threshold intends to repair it or to let one version consume the other.

Spoke to R. again. She says the old trees are dying — the ones over Grangegorman, the ones that anchor this side’s particular physics. When they go, the boundary goes. R. is frightened. I told her I would find evidence. Proof that Threshold is allowing the degradation deliberately. That the comfortable side benefits from our diminishment.

I have found something. In the alley behind Aughrim Street, where the membrane is thinnest. I will go tonight.

The last entry was undated. The handwriting had changed — looser, less controlled, as if written in haste or fear.

If something happens to me — look for R. She has the second set of notes. She will know what I was trying to do.

Nessa sat with the notebook for a long time, feeling the weight of a dead woman’s investigation pressing against her own. Sorcha had been investigating Threshold. Threshold had, presumably, investigated back.

V.

R. was a woman named Róisín who ran the pub, An Corr Éisc. She was tall, deliberate in her movements, and watched Nessa with the expression of someone who had already decided something and was waiting to see if Nessa would confirm it.

“You’re not Sorcha,” Róisín said, on Nessa’s third visit. They were alone in the pub, mid-afternoon, the heron sign creaking in a wind that carried the smell of the Grangegorman trees — that wet-bark, sap-heavy scent that didn’t exist in the other Stoneybatter, where the trees had been cleared for student housing two years ago.

“No.”

“You look enough like her to fool the others. Not me.”

“How did you know?”

Róisín wiped the bar with a cloth, a gesture so practiced it was closer to meditation than cleaning. “Sorcha had a way of listening. You listen differently. You listen like you’re gathering evidence. Sorcha listened like she was gathering weather.”

Nessa let that sit. It was accurate enough to hurt. “I’m trying to find out what happened to her.”

“She went to the thin place behind Aughrim Street. She went to get proof that Threshold was letting the boundary decay. And she ended up dead on your side of the street.”

“How do you know it was my side?”

“Because you’re here. If she’d died on this side, Threshold would have handled it quietly. Made the body fit. Given it the right clothes, the right coins, slotted it into whatever system needed a corpse. The fact that you found her — with all her wrong things intact — means she crossed over, or was pushed over, in the moment of dying. The body landed in the wrong Stoneybatter.”

Nessa thought about this. The body as a boundary violation. The murder as an act of geography.

“Do you have her notes? The second set?”

Róisín reached under the bar and produced a leather folder, its cover worn dark with handling. Inside: pages of maps, diagrams, measurements. Places where the two Stoneybrattens — Nessa couldn’t think of a better term — overlapped, bled, merged. The diagrams showed the boundary as a living thing, pulsing, thinning in some places and thickening in others. The thin places were marked with red circles. The alley behind Aughrim Street was the thinnest of all — the circle there was drawn over and over, the ink pressed deep into the page.

“Sorcha believed Threshold was letting this side wither,” Róisín said. “Not actively destroying it. Just… not maintaining it. The boundary needs tending. It’s been tended for centuries — by people on this side, mostly, the scholars and the tree-keepers and the people who understand the old mechanics. Threshold is supposed to protect both versions. But your version — the one over there — is the one that generates revenue, attracts development, produces what the world outside Stoneybatter would call economic value. This side produces —” She gestured at the pub, at the heron sign, at the faint luminosity leaking through the windows from the Grangegorman canopy. “Magic. Which has no GDP.”

“So Threshold lets the boundary thin because maintaining it is expensive and the side it protects isn’t profitable.”

“That’s the bureaucratic version. Sorcha thought it was more active than that. She thought someone in Threshold was deliberately weakening the boundary to expand your version of the neighborhood over ours. Gentrification at the ontological level.”

Nessa almost laughed. It was so perfectly absurd and so perfectly plausible — the same logic that drove every neighbourhood transformation she’d watched in Dublin for the past decade, the same logic that was putting skylights in the Kavanagh place and gutting the houses on Oxmantown Road, applied to the fabric of reality itself. The expensive version of the city consuming the inconvenient one.

“And she died proving it.”

“She died trying. I don’t know if she proved anything.” Róisín looked at her steadily. Her eyes were the colour of the pub’s stout — dark, with a warmth underneath that you had to look for. “Are you going to finish what she started?”

Nessa didn’t answer. She was looking at the photograph on the wall behind the bar — Sorcha and the woman who looked like Nessa, arms around each other, the pub’s sign visible behind them.

“Who is that?” she asked, pointing at the woman in the photograph. “The one who looks like me.”

Róisín’s expression changed. Not closing, exactly, but rearranging itself around something she’d been expecting Nessa to ask and dreading the arrival of. She set the cloth down and folded it precisely, as if the folding required her full attention.

“That’s Sorcha,” she said. “The other woman in the photo — the one you found dead — that was Bríd. Her sister.”

Nessa looked at the photograph again. Swapped the identities. The dead woman was Bríd. The woman who looked like Nessa — who looked more like Nessa than anyone should who had grown up on the wrong side of a perceptual boundary, who had never breathed the same air or walked the same version of the same street — was Sorcha. The scholar. The one who had studied the boundary itself, who had understood what was happening to it, who had disappeared.

“Where is Sorcha now?”

“Gone. Three months ago. She was here one evening — right there, at that stool — and the next morning her flat was empty. Bed made, mug washed, notebooks gone. No note. I checked the thin places. I checked the trees. I asked everyone I could think of.” Róisín’s hands tightened on the folded cloth. “Bríd took it hard. She wasn’t a scholar — she was a weaver, she worked at Seoighe’s — but she took Sorcha’s notes and went to the thin place behind Aughrim Street to find out what had happened to her sister.”

“And she died there.”

“And she died there. And now you’re here, wearing Bríd’s coat, living in Bríd’s flat, and you look so much like Sorcha that I almost — ” She stopped. Picked up the cloth again. Began wiping the bar in long, deliberate strokes that served no cleaning purpose. “You should go home, detective. Go back to your Stoneybatter. There’s nothing here that will end well for you.”

VI.

Nessa stopped going home.

It happened the way these things happen — not with a decision but with an accumulation of small failures to decide otherwise. A night in Bríd’s flat because it was late and crossing after dark felt dangerous. Two nights because she needed to re-read the notes. A week because Róisín had given her a name — a Threshold functionary who might talk — and she couldn’t pursue it from the other side.

She told herself it was operational necessity. She was building a case. She needed to be embedded. And in the station, during the diminishing hours she spent there, no one seemed to notice she was changing. Or they noticed and said nothing, which amounted to the same thing.

But the truth was simpler and more frightening. This Stoneybatter was making a claim on her. The heavy wool against her skin, the taste of tea from the blue mug, the creak of the pub sign in the Grangegorman wind, the way light moved here — slower, thicker, amber where her Stoneybatter’s light was thin and grey and noncommittal. The blacksmith’s hammer in the morning. The smell of bread from a bakery that used flour ground from a grain she’d never seen growing. She was beginning to feel at home, which was impossible, which was happening anyway.

And she was beginning to forget.

Small things first. She couldn’t remember her own phone PIN. She confused her superintendent’s name with a name from this side — called him Pádhraic instead of Patrick, which was the same name but the wrong version, and he gave her a look she couldn’t read. She found herself reaching for punt coins in shops that only took euro. One morning she woke in Bríd’s bed and could not remember which Stoneybatter she was supposed to go to, and the moment of confusion lasted longer than it should have — a full minute sitting on the edge of the bed, looking at the heron quilt, listening to the Grangegorman wind, before her own life reassembled itself around her like a coat she was putting back on.

Róisín noticed. Of course Róisín noticed.

“You’re merging,” she said. They were in the pub, late, the taps closed, a candle on the bar because the luminous trees outside had gone dark the way they sometimes did, for reasons Nessa had not yet learned.

“I’m tired.”

“You’re merging. It happens to anyone who crosses too often. The boundary isn’t just geographical — it runs through the people who cross it. You spend enough time on this side and your self starts… blurring. Sorcha studied this. She called it perceptual drift. The boundary thins inside you, the same way it thins in the streets. Eventually you stop being fully from one side.”

“How do I stop it?”

“You go home. You stop crossing. You let the boundary solidify around you again. You choose one Stoneybatter and you stay.”

“And the investigation?”

“The investigation was Bríd’s. Before that it was Sorcha’s. It’s a family inheritance of failure. You don’t need to be the next one.”

Nessa knew Róisín was right. She also knew she was not going to stop. Not because she was brave or dedicated — she was neither, or not particularly — but because the investigation had become a thing she couldn’t put down. Like Bríd’s coat, it fit her. Not perfectly. But close enough that taking it off felt like losing something she’d only just found.

VII.

She went to the thin place behind Aughrim Street at night. The same alley where Bríd’s body had been found — on the other side, in Nessa’s version. Here, the alley looked the same but felt different. The air was denser. The graffiti on the left wall was replaced by a mural of herons in flight, painted in that faint luminous pigment the trees produced. And at the far end of the alley, where the wall should have been, Nessa could see both versions simultaneously.

For a moment — a single, vertiginous moment — she saw the two Stoneybrattens layered on top of each other like a double exposure. The cranes and the trees. The cafés and the blacksmith. The satellite dishes and the luminous canopy. Both real. Both present. Both occupying the same streets with a mutual indifference that was, she understood now, the most violent thing she had ever witnessed. Not violence done by one to the other. Violence done by each to itself, in the act of refusing to see what stood beside it.

And there, at the boundary’s thinnest point, she saw the figure.

Tall. Motionless. Wearing a coat that was neither wool nor synthetic, made of material her eyes couldn’t categorize — it shifted between textures the way the neighbourhood shifted between versions. The figure stood where the two overlapped and seemed to occupy both simultaneously, which was — Nessa understood this with a clarity that felt like falling — what Threshold actually was. Not an institution. Not a bureaucracy. A state of being. A person who had given up the ability to see only one version in exchange for the authority to manage both.

The figure spoke. The voice came from very far away, or from inside her own skull. Both distances felt the same.

“Sorcha Ní Bhriain crossed the boundary with evidence that the eastern membrane was being allowed to decay. This evidence was accurate. The decay is managed, not accidental. The decision was made at a level you do not have access to and for reasons you would find reasonable if you understood them.”

“Did you kill her?”

“Sorcha Ní Bhriain’s location is not a matter for your investigation.”

“I’m not asking about Sorcha. I’m asking about Bríd. The woman in the alley. Her sister.”

A pause. The figure’s coat shifted. For a moment it looked like the green wool of Bríd’s coat and for a moment it looked like Nessa’s grey blazer and for a moment it looked like something else entirely.

“Bríd Ní Bhriain crossed the boundary at a point of maximum thinness while carrying documents that constituted a breach of perceptual protocol. The crossing itself was fatal. The membrane at that point cannot sustain the passage of a body carrying evidence of its own deterioration. The knowledge and the boundary are incompatible. One destroys the other.”

“That’s not an answer.”

“It is the only answer that is accurate.”

Nessa stood in the alley with Sorcha’s notes in her coat — Bríd’s coat — and felt the boundary pressing against her skin like a change in air pressure before a storm. She was carrying the same documents Bríd had carried. She was standing at the same thin point. The figure watched her with an attention that was not hostile, not sympathetic, not anything she could name. It was the attention of a system observing a variable.

“If I cross back,” she said, “with these notes. Will I die?”

“The membrane is thinner than when Bríd crossed. You might survive the passage. You might not. The probability is approximately equal.”

“And if I stay on this side?”

“Then the investigation ends. The evidence remains here. Your version of Stoneybatter continues to expand. This version continues to thin. In approximately eight years, there will be only one Stoneybatter. The trees will be gone. The luminescence will be gone. The herons will be a motif on coffee cups in a café that sells flat whites to people who have never seen an actual heron.”

“And if I cross?”

“Then the evidence enters your version. Threshold will be forced to act. The outcome is unpredictable.”

Nessa looked at the notes. Sorcha’s handwriting. Bríd’s blood, still faintly visible on the leather folder where Róisín had not been able to clean it fully. She was wearing Bríd’s coat and standing in Sorcha’s neighborhood and carrying a dead woman’s evidence and she could not, in that moment, remember with certainty which woman she was. The merging Róisín had warned her about was not a metaphor. She could feel it — two sets of knowledge, two sets of habits, two ways of seeing the same street, pressing against each other inside her like the two Stoneybrattens pressed against each other outside.

She walked toward the thin place. The air thickened. The mural and the graffiti occupied the same wall. The bins and the boxes existed in both versions, identical and indifferent. She kept walking.

VIII.

This is what the case file says:

On the morning of October 19th, a woman was found unconscious in the service alley behind Aughrim Street, Stoneybatter, Dublin 7. She was wearing a dark green wool coat, double-breasted, with a label reading SEOIGHE & DAUGHTERS, MANOR STREET. She carried a canvas bag containing a leather folder of documents, a purse with unidentified coins, and a phone of unknown manufacture. She had no identification.

She was taken to the Mater Hospital, where she was treated for hypothermia and an unspecified neurological event. She gave her name as Nessa Tiernan. She was identified by colleagues from Stoneybatter Garda Station as Detective Superintendent Nessa Tiernan, who had been on leave for three weeks following what her superintendent described as “a personal matter.”

The documents in her bag were examined and found to contain maps, diagrams, and notes in Irish that described, in technical detail, the existence of a second version of the Stoneybatter neighbourhood occupying the same physical space as the first. The notes referenced an organisation called “Threshold” and alleged a deliberate policy of allowing one version to decay for the benefit of the other.

The documents were forwarded to an unspecified department. The case file was sealed.

Detective Superintendent Tiernan returned to duty in November. Colleagues noted that she seemed “different” — quieter, more attentive to the physical details of the neighbourhood, occasionally pausing in the middle of Manor Street to look at a section of wall between the credit union and the Filipino grocery. She was effective in her work. She did not discuss the case or the three weeks she had spent on leave. She had developed a habit of turning coins in her fingers — coins her colleagues assumed were euro, though none of them looked closely enough to see the heron.

This is what Róisín says:

Sorcha came back.

Not immediately — there were weeks of uncertainty, weeks when the flat on Kirwan Street stayed empty and Róisín checked it every morning, opening the blue door and standing in the kitchen and looking at the cold mug on the table. Then one evening in late October, a woman came into the pub wearing Bríd’s coat, carrying Bríd’s bag, and sat at the bar with a tiredness that went deeper than the body.

She looked like Sorcha. Not like Bríd — like Sorcha. The jaw was right, the way the shoulders sat was right. She knew the neighbours’ names, the pub’s hours, where the good bread came from, which lanterns along the Grangegorman path needed re-lighting and which kept their glow through winter. She took up the research — the mapping, the measurements, the careful documentation of the boundary and its thinning.

But Róisín noticed differences. The woman listened differently now — less like she was gathering weather, more like she was gathering evidence. She reached for her tea with her left hand instead of her right. She paused sometimes in the middle of conversation, as if translating from a language no one else could hear. And she had a habit Sorcha had never had: she turned coins in her fingers, round and round, feeling their weight, as if reminding herself which currency she was carrying.

“Are you Sorcha?” Róisín asked, once, late at night, after too much of the pub’s dark stout, with the candle burned down to a stub and the Grangegorman trees dark outside.

The woman looked at her for a long time with an expression that was, Róisín decided later, the saddest she had ever seen on a human face.

“I don’t know,” she said. “I crossed the boundary and I came out the other side and I don’t know which side I started on. Both feel like home. Neither feels like home. I have two sets of memories and they’re both mine and they’re both someone else’s.”

“That’s not an answer.”

“It’s the only answer that’s accurate.”

On Manor Street, between the credit union and the Filipino grocery, there is a section of wall that is the colour of dried blood. If you look at it directly, it is a wall. If you look at it from the corner of your eye, in the amber light of a particular kind of evening, it might be a door.

Most people walk past it. This is how most people walk past most things. The eye registers, the brain categorizes, and the feet keep moving. It is not malice. It is not conspiracy. It is the ordinary, daily, devastating act of choosing one version of the world and unseeing the rest.

The boundary is thinner than it was. Whether it will hold for another decade or collapse in five years is a question that someone is investigating — a woman in a green wool coat who pauses on Manor Street and looks at the wall and sees something the rest of the city has agreed not to see. Whether she is a detective from the comfortable side who crossed over and lost herself, or a scholar who was lost and crossed over and found herself in a detective’s life, depends on which Stoneybatter you are standing in when you ask. Both versions are supported by the evidence. Both women are real. The distance between them is the width of a door that may or may not exist, on a street that is the same street and a different street, in a city that has always been two cities pretending to be one.