The cushion was purple. That was the first thing Jack Morrisey noticed about it—not the strange symbols embroidered along the edges, not the faint metallic smell that reminded him of the Argonne in November, but the color. A deep, impossible purple that seemed to glow in the dim light of his Ford Model T. He had bought it from a junk shop in Greenwich Village for two dollars. The shopkeeper said it came from the estate of a professor who went crazy. Jack did not care why it was there. He cared that it made his seat more comfortable, and that it cost less than the replacement upholstery he could not afford.

He was twenty-nine years old. He had come back from France with a limp in his left leg and a mind full of dispatches that nobody wanted to read. He wrote poetry on napkins in speakeasies and sold them for five dollars to people who thought they were brilliant. They were not brilliant. They were honest. There is a difference.

The first man who vanished from Jack's cab was fat and reeked of gin and bad decisions. He got in near Wall Street, told Jack to drive, and settled onto the purple cushion. Jack drove. The man laughed at something on the radio. And then the seat was empty.

Not stepped out. Not ran away. Empty. As if the man had never existed.

Except he had. On the purple cushion sat his fedora, his gold watch, his cigar case, and a leather portfolio filled with stock certificates. Jack opened it. The certificates belonged to Harold Grimshaw, a factory owner who had been caught paying his workers half what he promised. Jack looked at the empty seat, looked at the portfolio, and felt something he had not felt since the war: purpose.

He could turn this in. But he remembered the letters from the men who did not come back from France. He remembered their mothers writing to him because he was the one who could write good letters. He looked at the purple cushion. He started driving.

He became a vigilante of the invisible. A factory owner who employed children got in his cab, vanished, and left behind a ledger that Jack anonymously sent to the labor board. A landlord who let tenements rot got in, vanished, and left behind property deeds that Jack delivered to the families living in squalor. A policeman who took bribes from the docks got in, vanished, and left behind a badge and a list of names.

Each disappearance was a small justice. Each vanishing was a correction. Jack told himself he was not a murderer—he was a surgeon, cutting out the rot. The cushion was his scalpel. The fourth dimension was his operating theater.

But the cushion had a cost. Jack began to notice that every time someone vanished, something of his own faded too. His reflection in the rearview mirror was slightly less sharp. His handwriting became harder to read. The poets who bought his napkin poems said his voice sounded thinner, as if he were speaking from the bottom of a well.

He was paying for each disappearance with a piece of his own existence.

A woman got in near Central Park. She was elegant, sharp-eyed, with the posture of someone who had never asked permission for anything. She said her name was Eleanor Vance and she was a journalist. She had been writing about the disappearances—the factory owners, the landlords, the corrupt officials. All men who hurt people. All men who vanished from Jack's cab.

She looked at him and said, "I know what you are doing, Mr. Morrisey. And I know what the cushion is doing to you."

She was not here to expose him. She was here to warn him. She told him about a man in Chicago who had a similar cushion and used it for a year—and then he vanished too, and nobody remembered him. Not his wife. Not his friends. Not even his own handwriting in his notebooks. The cushion does not just erase people from the world. It erases them from memory. From history. From everything.

Jack had one ride left in him. One final disappearance. He could use it on a man who ran a sweatshop that employed hundreds of children—a man who had bribed every inspector and bought every judge. A man whose disappearance would save hundreds of lives. But Jack would also disappear. Not just from the world—from everything. He would never have existed.

Jack drove to the sweatshop. He picked up the owner, a man named Harrington, who got in without a word, knowing exactly who Jack was. They drove in silence through the streets of Manhattan. The city blazed with light—neon signs, streetlamps, the windows of tenements where families ate dinner and laughed and loved and did not know that a man was about to sacrifice his entire existence so that their children might grow up free.

Jack stopped the cab. He looked at Harrington and said, "You are going to disappear." Harrington nodded and said, "I know." Jack said, "Do you forgive me?" Harrington said, "I do not get a choice in that."

Jack turned to the purple cushion. He sat on it himself, with Harrington still in the back seat. The velvet glowed purple in the streetlight. The city held its breath. And then—nothing.

The next morning, nobody remembered Jack Morrisey. Not the poets. Not the mechanic who fixed his Ford. Not the woman at the diner who always gave him extra coffee. The yellow cab was gone. The purple cushion was gone. Jack Morrisey never existed.

But the sweatshop closed. The children went home. And on the corner of 42nd Street, where Jack used to wait for fares, there was a small patch of purple flowers that nobody planted and that bloomed every autumn, even when the frost came early.