Seven Minutes

Chapter 2

Fingerprint

She badged in at twenty to ten, and the door made the same noise it always made, which struck her as scandalous.

The unit occupied two floors under George Square, below street level, along a corridor nobody crossed by accident. It was eighteen degrees all year round and there was a permanent background noise, a low note of ventilation that you stopped hearing after a week and missed terribly on the days it was switched off. Ellie loved the place the way you love a well-kept cellar.

Priya looked up over her screen.

— Well.

— Do not start.

— I did not say anything.

— You said well.

— It is a neutral word.

— It is never a neutral word.

Priya Raghavan had worked opposite her for six years and kept a mental register of everything that never happened. She put down her tea.

— Four years, she said. I will check, but I think it is four years.

— The bus.

— Yes.

Priya looked at her for another second, decided something, and went back to her screen. It was one of the rarest qualities Ellie knew of in a human being: knowing when to stop.

Priya was forty-three, had two daughters, a husband who taught geography and a theory about the world that she set out roughly every two months: people do not lie, they leave things out, and so you have to listen to the gaps. She had arrived in the unit in 2020 after four years spent studying the silent corruption of magnetic media, which, she said, was the best possible preparation for family life.

She brought laddoos at Diwali and shortbread at Christmas, and she had once explained to Ellie, entirely seriously, that the basement of George Square was the only place in Edinburgh where you could work without being interrupted by the weather.

They had seen each other eight hours a day for six years and had never been to each other's houses.

She put her phone on the desk, next to the keyboard, and stood in front of it for a moment without touching it.

Then she did what she would have done for any object handed to her in a doubtful state. She got out the cable, connected the phone to the workstation, and began with the one action that, in her profession, comes before all the others: she calculated the file's fingerprint.

A fingerprint is a string of sixty-four characters obtained by running the entire contents of a file through a mathematical mincer. Change a comma, change a pixel, change one bit lost in the middle of two million others, and the whole string becomes unrecognisable. It is the only thing in the world that lets you assert that a digital object is the one you think it is. Ellie calculated hundreds of them a day, and thought about it no more than she thought about breathing.

She wrote it out on a Post-it, by hand, because she had always done that.

Then she opened the full metadata. Not the phone's polite display, which shows three lines and a map: the whole block, as written in the file, with its empty fields, its duplicates and its errors.

It was all there.

Device model: hers. Serial number: hers. Main lens, aperture, exposure time, sensitivity, white balance, system version, camera application identifier. A badly lit interior, in the morning, handheld. Nothing inconsistent. Nothing exotic. No retouching software had touched the file, no converter, no social network — and that always leaves traces, always, because those tools sign their passage like dogs.

She moved on to the sync log.

The account kept an account of everything: what went up, what came down, at which second, from which device. She scrolled down to Friday 13 March.

08:43:07 — modified — item 4F2C-…

She read the word again.

Not added. Not imported. Modified.

She looked for the item identifier in the history, and the identifier had existed since 9 August 2024.

It took her twenty minutes to restore the previous day's backup onto an isolated working disk, because the backup ran to a hundred and eighty gigabytes and the campus network had not been built for private emergencies.

While it ran, she scrolled back through the photo library by hand.

January went past under her thumb. She had spent four days at King's Buildings that winter, on a data rescue: an inventory series dated the 22nd, dozens of grey, cold thumbnails. A cryostat under its cover. A serial label stuck crooked on a flank of steel. A visitor badge left on a bench, with the date printed on it.

She carried on without stopping.

The backup finally opened. She navigated to 9 August 2024, and the image was there.

A wall in Leith, painted brick, with a blocked-up door and a planter somebody had hung two and a half metres off the ground, presumably so that it would not be stolen. She remembered it very well. She had photographed it one Sunday because the planter had made her laugh, and she had sent the photograph to her sister, and her sister had replied with a single word.

Her sister had replied: why. Without a question mark. That was Morag all over.

She scrolled the backup to the item and read the technical record in full, line by line, twice.

Same identifier. Same position in the album. Same original second.

Different contents.

She stood up, took three steps, came back. A file that degrades does not become a different photograph: it becomes noise, banding, half a green frame, a grey square. A file that degrades does not invent a bedroom. She knew the catalogues of damage by heart, she had published a chapter on them, and there existed no mechanism of corruption in the world — not one — that turns a brick wall into a room with a man lying on the floor.

Ellie put the two files side by side and ran a byte-by-byte comparison, which was of no use whatsoever since she already had both fingerprints in front of her and they did not share a single character. She did it anyway. She watched the progress bar run to the end and display what she already knew.

Method was the word she used when people asked why she did this job. You do not trust your memory, you do not trust your impression, you do not trust what the system deigns to display: you go and get the bytes and you count them. For twelve years, method had always ended up producing something. A misconfigured path, a clock running slow, an operator who had performed the same action twice.

That morning, method produced this: the file was authentic, produced by her device, never retouched, and it had replaced a photograph of a wall in Leith taken nineteen months earlier.

She realised her hands were cold.

At around noon she went up to the coffee machine on the second floor and stood in front of it without putting a coin in, reading the list of drinks.

She had a sentence ready. She had built it on the way up the stairs, taking out the words that would make anyone jump: I have a file that modified itself and I cannot explain it. It was true, it was precisely her field, and Priya had spent four years on the corruption of storage media before coming here. In ten minutes there would have been two of them.

Priya came up behind her with her cup.

— You are blocking the queue.

— There is nobody here.

— I am somebody.

Ellie stepped aside. Priya pressed her button, and the machine began making its throat-clearing noise.

— Go on, said Priya without turning round.

— What?

— You have had a question since this morning. You have been turning it over since this morning. You have the same face you had when you found the duplicate thesis, except that this time you did not tell me at nine.

Ellie opened her mouth.

What stopped her was not the fear of looking ridiculous. It was something much smaller and much more effective: if she described the file, Priya would ask to see it. That was normal. It was what she herself would have asked, immediately, without thinking. And she saw very clearly the scene that would follow — Priya leaning over the screen, the silence, and then the way Priya would look at her afterwards, today, tomorrow, in six months.

— Something to do with an identifier, she said. An old deposit. It is fine.

Priya took her cup and considered her a moment too long.

— All right.

She went. Ellie put a coin in the machine, took a coffee she did not want, and drank it to the bottom because she had paid for it.

At one o'clock, Priya put a sandwich down beside her without comment and left again.

Ellie opened a ticket with the university IT service, which made no sense since it was her personal account, and then a second one with the photo service provider, which made a little more. She described the facts in order, without adjectives, with the fingerprints, the timestamps and the identifiers. She read it back. She removed the sentence where she said it was impossible, because a ticket that begins by calling a thing impossible always ends up at the bottom of the pile.

She did not write what the image showed.

She put the thought to herself clearly, at that moment, watching the cursor blink in the description field: I will not say what is on it. She put that down to common sense. You do not tell a help desk that sort of thing.

The truth was simpler and she knew it already: as long as she did not say it, it had not quite happened.

At five o'clock, she came back to the size.

It was the only figure in the file she had not yet attacked, and she had saved it for last without admitting it to herself, the way you save the last door.

1,941,224 bytes.

She took out a sheet of paper and listed the possible settings on her device, because there were not thirty-six of them. Maximum quality: between four and six megabytes for a scene of that kind, more if there was grain, and there was grain. Space-saving format: between one and two, but the space-saving format leaves a signature in the metadata, and the signature was not there. Screenshot: fixed dimensions, and these were not them. A frame extracted from a video: she checked, and it was not that either.

She took three photographs of the corridor with her own phone, in the half-light, handheld, so as to have points of comparison from the same day. 4.8 MB. 5.1 MB. 4.6 MB.

She looked at them for a long time, lined up under the line of the impossible file.

A camera has no opinion. It records a quantity of information, and that quantity depends on what is in front of it: detail, noise, contrast. You can make it vary, you can reduce it, but always through a setting, and a setting shows.

Here there was no setting. There was an image that should have weighed five megabytes and weighed two.

As though something had compressed it on the way. As though the way had been long.

Ellie switched off her screen, sat in the blue dark of the basement, and for the first time since morning she had no hypotheses left to try.