The first rule of archive work is never to run unless the building is on fire.

The second rule, Mabel discovered only after the Thursday File attempted to escape into a fold in time, was that exceptions would not be issued in writing.

"Is that hole supposed to be there?" she asked.

The silvery crease in the back wall fluttered as if insulted by the word hole. It had widened into a narrow doorway lined with static. On the other side Mabel could see shelves, lamplight, and the unmistakable shape of a potted fern she knew for a fact had died in the foyer three winters ago.

Inspector Vale tucked the file under his arm. "Supposed is an optimistic word."

Mrs. Vale-Smythe pinched the bridge of her nose. "It has opened into overflow."

"Overflow where?"

"Thursday," said Vale.

Mabel considered the two of them. Mrs. Vale-Smythe stood with all the grim dignity of a person who had balanced books against the laws of nature and found the laws of nature embarrassingly vague. Inspector Vale, still damp from dying eight years in the future, looked pleased to have company.

"I don't care whether that is a place or a diagnosis," Mabel said. "You are both making an effort to be unhelpful."

"Fair criticism," Vale replied. "Would you like the absurd explanation or the worrying one?"

"Are they different?"

"Not in local government."

Mrs. Vale-Smythe took over. "Blackwater's town clocks were synchronized in 1892 by a railway engineer with more curiosity than sense. Every so often the system produces an eddy. Lost moments gather. Repeated minutes stack up. In most towns this becomes folklore. In Blackwater it becomes filing."

"Hence the Thursday File."

"Hence the Thursday File."

Vale nudged the crease with his umbrella. "And hence this door. Someone has been using the eddies deliberately. The pattern is too neat."

Mabel looked at the file. "Then we read it."

"Certainly not," snapped Mrs. Vale-Smythe.

"Certainly yes," said Vale.

"You are dead."

"Intermittently. Try not to let it dominate the conversation."

The file chose that moment to tremble in Vale's hands like an indignant spaniel.

"I vote we go where it wants," Mabel said.

Mrs. Vale-Smythe stared at her for a long moment. "Miss Quince, have you always been reckless?"

"No. I was hoping to grow into it gradually."

They went through the crease in single file, because there are only so many ways to enter a malfunctioning day.

On the other side, the archive had rearranged itself into something almost festive. The lights were warmer. The air smelled of tea leaves and machine oil. The shelves wore date labels that shifted when Mabel tried to focus on them: THURSDAY, THURSDAY, LATE THURSDAY, A BIT OF THURSDAY MISPLACED BEHIND 1981.

At a long table in the center of the room, six clerks were having tea.

All six were the same clerk.

Mabel stopped so abruptly that Vale nearly walked into her.

"Mrs. Trundle," she whispered.

The women at the table looked up as one. Each wore the same navy cardigan and the same look of concentrated annoyance, though one had a yellow ribbon in her hair, another wore spectacles she had never seen Mrs. Trundle use, and a third appeared to be from an era when hemlines had given up.

"Tea break," said one of them. "You can join if you've brought your own biscuits."

"How many of you are there?"

"At present?" asked another. "Or spiritually?"

Vale tipped his hat. "Multiple occupancy due to repeated Thursdays. Harmless if no one panics."

"And if someone panics?"

"Then there are seven Mrs. Trundles, all cross."

That, Mabel felt, was warning enough.

Mrs. Vale-Smythe marched to the table. "Has anyone seen an unauthorized removal request?"

The Mrs. Trundles conferred with themselves in a brief, furious murmur.

"Brown envelope," said Ribbon Mrs. Trundle.

"Marked RAILWAY," said Spectacles Mrs. Trundle.

"Taken by a gentleman with cuffs full of coal dust," said 1960s Mrs. Trundle.

"He smelled of platform tea and dishonesty," added a fourth, which struck Mabel as useful phrasing.

Vale opened the Thursday File at last. Inside were typed notes, handwritten marginalia, and a running index of irregularities whose existence made the rest of Mabel's week feel almost offensively straightforward.

14 March 1971 - Mayor absent from ribbon-cutting due to duplicate noon.

2 July 1983 - Brass band repeated refrain until morale improved.

Unknown date - Platform Zero observed. Do not board unless invited.

Attached to the page with Platform Zero was a luggage tag from Blackwater Station and half of a train ticket stamped NOT YET.

"There's your railway," Mabel said.

Vale nodded. "Platform Zero only appears when a schedule is wrong enough to become metaphysical."

"Naturally."

Mrs. Vale-Smythe was already scanning the rest of the file. "Someone has removed three index cards."

"What was on them?" Mabel asked.

"Access notes for the municipal chronometer, the signal box beneath the west platform, and..." She stopped.

"And?" Vale prompted.

"Tea allotments."

Mabel blinked. "Tea allotments."

"Do not underestimate tea in this town," said all six Mrs. Trundles in perfect chorus.

Before anyone could say anything wiser, a bell rang somewhere deep in the shelving. It sounded like a railway signal trying to remember a hymn.

The far end of the room blurred. Rows of boxes drew aside with stately irritation, revealing a narrow passage lined with old station clocks. Each face showed a different time. One showed Tuesday.

At the end of the passage stood a small refreshment trolley.

Bertie Pikes was leaning on it, reading a newspaper dated three months from now.

"There you are," he said. "You're late."

"Bertie," said Mabel, "how are you here?"

"Lift by the service stair. Much easier than dying first."

Vale looked offended. "That was one time."

Bertie folded the paper. "I took the liberty of following the kettle. Also, I thought you might want these."

From beneath the tea towels he produced three index cards.

Mrs. Vale-Smythe inhaled sharply. "Where did you get those?"

"Found them tucked inside the biscuit ledger in the canteen. Suspicious place for anything important. One never looks carefully in the vicinity of a stale digestive."

Vale took the cards. "Good man."

Mabel peered over his shoulder. Each card contained a note in the same stern typing as the memo from tomorrow.

CHRONOMETER KEY TEMPORARILY RELOCATED.

PLATFORM ZERO ACCESSIBLE VIA SIGNAL BOX.

DO NOT LET MR. SPATCHCOCK HANDLE THE MINUTES.

"Who is Mr. Spatchcock?" Mabel asked.

Bertie and Mrs. Vale-Smythe answered together.

"Deputy Town Clerk."

Vale added, "A man whose fingers have always looked slightly dishonest."

Mabel turned the last card over. On the back, in her own handwriting, was a single sentence:

If you are reading this, he has already hidden the week.

For the second time that day, Mabel was forced to accept that her future self had developed a flair she was not sure she approved of.

"Right," she said. "We're going to the station."

Mrs. Vale-Smythe drew herself up. "Miss Quince, this is a temporal investigation involving civic infrastructure, a dead detective, and probable railway trespass. It is not suitable for junior staff."

"With respect," Mabel said, "junior staff are the only people currently receiving instructions from tomorrow."

Bertie poured tea into three chipped cups and one extremely formal mug.

"Best drink up," he said. "If Platform Zero is open, it usually closes at lunch. The town dislikes dramatic work extending into the afternoon."