The Cipher Room

The needle had not moved in three weeks.

It sat under its glass in the walnut box on the top shelf of the studio in Fishtown, between a coffee can of brushes and a jar of gold size, and it pointed south-west. Not roughly. Exactly. Mara had checked it with a phone compass, with a map, with a length of string pinned to the floor, and then, feeling foolish, with nothing at all, just standing in the middle of the room at two in the morning and looking. South-west, across the river, across Delaware and Maryland, toward Washington, steady as a finger laid on a page.

Everything else had been different, and the needle had been the only thing that stayed the same.

The receipt in the kitchen drawer still said Tenney & Daughters. Mara had looked at it so many times the fold had gone soft. Marisa's younger daughter taught history at Central High School, and once, when Mara drove out to Germantown to return a borrowed hand truck, she was there, sorting a box of old schoolbooks on the porch, and said cheerfully that she spent every September teaching sixteen-year-olds to be furious about one paragraph.

"Which paragraph?"

"The trade passage. Execrable commerce. Jefferson blames the King for the slave trade, and then they all go home to the people they own." She shrugged. "Best lesson of the year. They never forget it."

Mara had gone home and read about the Charleston wharf museum and its long wall of names: the ships that were never fitted out, the voyages that were never made, because in this world the Constitution had banned the import trade from the first day it took effect. Tens of thousands of people, the historians said, at the least. It was a wall of absences. Mara had stood in the kitchen and read every name on the museum's website, and had not been able to decide whether it was the best thing Mara had ever done or only the least bad.

It was not peace, exactly. It was a kind of homesickness for a world nobody else remembered, mixed with a responsibility that would not lie down. And above it all, on the shelf, the needle.

On a Thursday in the middle of July, Mara took the walnut box to the corner of Seventh and Market at first light.

There was nobody about but a street sweeper and a man asleep in the doorway of the bank. The reconstructed house stood on its corner in the grey, narrow and brick, with its shutters closed. Mara opened the box, lifted out the compass, and raised the two brass sights, and did not look along the needle at all, but east, down Market toward the river, toward the place and the summer that Mara knew best in all of history.

Take me back, Mara thought, absurdly, the way you speak to a car that won't start.

The needle moved. It swung, smoothly, until it lay across the sights. Then it went on swinging, past them, slow and stubborn, like a weathervane in a wind that only it could feel, round to the south-west again, and settled there, and trembled, and was still.

Mara tried three times. Three times the needle went past the sights and came back to Washington.

Inside the lid, in the faded ink of the unknown hand: Every line has two ends. Not three. Not a way back to the start. Mara stood on the corner, while the sweeper went by and the sun came up behind the river, and understood, in the way one understands a door that has been locked from the other side, that Philadelphia was finished. The compass had taken Mara there once, and it would not take Mara there again.

The train left Thirtieth Street at ten.

Mara had the walnut box in a canvas bag on her knees the whole way, past Wilmington and Baltimore and the long marshes, and in the afternoon stood on the steps of Union Station in a heat like a damp towel and opened the lid in the shade of a column.

The needle had shortened its bearing. It no longer pointed at a city. It pointed at a place, somewhere west of the Capitol dome, and the place was a long walk away in that heat.

Mara followed it on foot, as the light went gold and then orange: down past the Capitol, along the Mall, across the hot gravel and the tourists and the ice-cream carts. Every few hundred yards Mara stopped in a patch of shade and opened the lid, and every time the needle had turned a few degrees more, patiently, the way a surveyor's line is walked: one stake to the next, no shortcuts. Past the Washington Monument it swung north. Past the Ellipse it swung north-west. A child on a scooter asked if it was a treasure map, and Mara said, truthfully, that Mara did not know yet.

It pulled toward the White House, and then, oddly, past it, to the west, to a great grey granite building that stood next to it like an overdressed uncle. Columns, stacked one storey on another. Mansard roofs. Chimneys like a row of chess pieces.

The Eisenhower Executive Office Building, said a sign. Mara had read about it on the train. Before this building there had been another on the same ground, plain and brick and smaller: the old War Department, where, in the last years of the Civil War, Abraham Lincoln had walked over from the White House almost every day to read the telegrams.

At the corner of Seventeenth Street and Pennsylvania Avenue the needle stopped searching. It pointed straight down, or as near straight down as a compass can, at a square of pavement by the iron fence.

Mara knew the rules now, or most of them. The needle points at a hinge, never north: a day when the country could have gone more than one way. At first light, stand where it settles, raise the sights, and look along it. You arrive on that spot, on the hinge's first day, dressed for it, with coin in your pocket and a letter of introduction in a hand you do not know, signed E.P. Whatever is in your pockets comes too; nothing else does. You stay until the day is decided, and the needle swings north. What you change stays changed, and only you remember it. And you can say what you know, as plainly as you like, and you will be taken for mad.

Mara spent the night in a small hotel on I Street, not sleeping.

The War Department had stood on this corner from 1820 until the 1870s; the telegraph office had been on its second floor; the President had come over, the books said, in all weathers, often late at night, in a shawl and carpet slippers, to sit at a clerk's desk and read the war off the wires. Mara read until two, propped on the hotel pillows with the phone's light on her face. Which day? There was no way to know. The needle did not give dates. But Mara knew which spring the old War Department had mattered most, and knew how that spring had ended, in a theatre ten blocks east, on a Friday night, and found herself reading the same account over and over, the way you press on a bruise: the box, the play, the boarding house across the street, the long night, the morning.

A hinge, Mara thought. A day the country could have gone more than one way.

Before dawn Mara walked back to the corner.

There were uniformed officers at the White House gates, and a jogger, and a delivery van idling. Nobody paid any attention to one more tourist with an old brass instrument. Mara stood on the square of pavement, opened the walnut box, and waited for the sky over the Treasury to go from black to grey.

Then Mara raised the two brass sights, and put an eye to the slit, and looked along the needle.

Somewhere close by, a cannon fired.