Dr. Samir Hashemi had lived in Greenfield, Illinois, for eleven years when the first note appeared under his office door. It was a Thursday in late September 2005, the sky outside his window the flat white of an old television tuned to a dead channel, and the note was typed on department letterhead and unsigned. It said simply: Some of us are concerned.

He read it three times and then put it in his desk drawer. Outside his office, the corridors of Rensselaer College were filling with the noise of the fall semester. Students in flip-flops and university sweatshirts, their iPods still playing the White Stripes and Green Day, their mobile phones buzzing with text messages about parties and papers due. Samir was an associate professor of comparative literature, specialising in medieval Persian poetry. He had been at Rensselaer for eleven years. He had tenure. He had published two books and twenty-three articles. He had served on eleven committees. He had a wife, Amira, and a daughter, Leila, who was eight years old and learning to play the violin. He was, by any reasonable measure, a success.

The first thing that changed was the department meeting. It was the first week of October, a Tuesday at four o'clock, and Samir had been on the curriculum committee for six years. Every fall, he was reappointed without discussion. This fall, the chair — a pink-faced Chaucer scholar named Howard Whitcomb — announced that the committee slots would be decided by election. Democracy, Howard said, smiling in that particular way that meant he was uncomfortable. Everyone deserves a voice.

Samir was not elected to the curriculum committee. He was not elected to any committee. He sat in the back of the conference room with his hands folded and watched his colleagues vote. Marcia Evers, who taught postcolonial theory and had once called Samir a kindred spirit, did not look at him. Tom Bredon, who had co-authored an article with Samir on Rumi's influence on medieval troubadour poetry, voted against him. The vote was by show of hands, and Samir saw every hand that went up and every hand that stayed down.

After the meeting, Tom caught up with him in the corridor. Listen, Samir, it is not personal. It is just that with everything going on right now, with the war and the security situation and Homeland Security raising the alert level to orange again, some of us thought it might be better if you took a step back. Just for a bit. Just until things settle down.

Samir looked at him. Tom was holding a paper cup of department coffee. The coffee was terrible. Everyone complained about it. It was one of the things they all shared.

What things, Samir asked. What things are going on.

Tom looked uncomfortable. You know. The whole situation. The Middle East. People get nervous.

I am from Cleveland, Samir said.

Tom nodded. Of course. Of course you are. It is not about you personally. It is about perception. You understand.

Samir did not understand, but he said that he did anyway, because that was what you did when a colleague used the word perception in that tone of voice. He went home and told Amira, who was a paediatrician at the county hospital, and she said nothing for a long time and then said that she had noticed something similar. The nurses had stopped asking about her weekend. The other doctors had stopped inviting her to lunch. Small things. Negligible things. Things that could be explained by busy schedules and short staffing and the general exhaustion of people who worked sixty-hour weeks in public health. Things that, taken individually, meant nothing at all.

The second thing was the bake sale. Every October, the elementary school held a harvest festival, and parents were expected to contribute something to the bake sale table. Amira always brought maamoul, the little date-filled cookies her grandmother had taught her to make, and they were always popular. This year, the PTA president — a woman named Susan Delacroix with frosted blonde hair and an SUV with a Support Our Troops ribbon magnet — asked Amira if she might bring something else. Something more traditional, she said. You know, for the kids.

Traditional, Amira repeated.

American, Susan said. Something American. I hope you understand.

Amira brought brownies from a box mix. They tasted like chocolate-flavoured cardboard. Nobody complained. Leila, who was eight, asked why they were not bringing the cookies this year, and Samir told her that they had been too busy to make them, which was a lie, and Leila looked at him in the particular way that eight-year-olds look at their parents when they know they are being lied to but have not yet learned to call it out.

The third thing was the Dean's coffee. Every semester, the Dean of Arts and Sciences held an informal coffee for tenured faculty, a chance to talk about university business in an atmosphere of collegial relaxation. Samir had been going for a decade. Two days before the coffee, the Dean's assistant called to say that the event had been cancelled due to a scheduling conflict. Samir later learned from a junior faculty member that the coffee had gone ahead as planned. He had simply not been invited.

That night, he sat in his study and looked at the books on his shelves. The leather-bound Rumi his father had given him when he finished his doctorate. The critical edition of Attar that had taken him three years to annotate. The framed photograph of his parents in front of the Cleveland Public Library, where his father had worked as a cataloguer for thirty-two years. His father had come to America in 1963, a young Iranian immigrant who believed with every fibre of his being that education was the ladder and that if you climbed high enough and worked hard enough, nobody could push you off. And his father had been right, mostly. The country had been good to them. The country had let them climb.

But the ladder was starting to feel very narrow, and Samir was starting to feel very high up.

The fourth thing was the student evaluations. Every semester, the college distributed anonymous evaluation forms, and every semester Samir received the usual mix of praise and complaint. This semester, there was a new category of comment. A student wrote that Dr. Hashemi seemed to have a certain perspective on world events that was not entirely balanced. Another wrote that while the course material was excellent, the instructor's background sometimes coloured his interpretation of texts in ways that students might not be equipped to critically evaluate. A third wrote, more bluntly: I do not feel comfortable in this class given current events.

The Dean's office sent Samir a memo requesting a meeting to discuss the evaluations. The word bias was used. The word inclusive was used. The word community was used seven times in two pages. The memo was cc'd to the Provost and the Director of Human Resources.

Samir sat in his office and read the memo five times. On his desk was a stack of papers to grade, essays on the conference of the birds in Attar's Mantiq al-tayr, the great allegorical poem about a group of birds who set out to find their king and discover that the king is themselves. He had been teaching this poem for eleven years. He had written a book about this poem. He was one of six people in the United States who could read it in the original Persian and explain its metrical structure and its theological implications. He was, in his field, an authority.

But none of that seemed to matter anymore. What mattered was perception. What mattered was comfort. What mattered was the slow, subtle, perfectly reasonable process by which a community decided that one of its members was no longer quite a member, was something slightly other, something that might need to be watched, or managed, or gently, politely, regrettably excluded.

The fifth thing was the neighbour. The Hashemis lived on Sycamore Street, a quiet block of two-storey houses with front porches and maple trees and Halloween decorations that went up every October without fail. Their neighbours on the left were the Johnsons, a retired couple who had been friendly in a distant Midwestern way. Mrs. Johnson brought over a casserole when Leila was born. Mr. Johnson helped Samir clear the driveway after the big snowstorm of 2003.

In November, Samir noticed that the Johnsons had stopped waving when he pulled into the driveway. He noticed that their dog, a golden retriever named Buddy who used to bound over to the fence for treats, was now called back whenever Samir approached. He noticed that the Johnsons had invited the neighbours on the right for dinner, and the neighbours across the street, but not the Hashemis. He noticed all of this and told himself it was nothing, that people got busy, that retirement was stressful, that he was being paranoid.

Then Leila came home from school and said that a boy in her class had asked her if her daddy was a terrorist. She said it in the same tone she used to report what she had eaten for lunch. She did not understand the question. She did not understand why her father sat down very suddenly on the kitchen chair and did not speak for a long time.

That night, after Leila was in bed, Amira said: We should move.

Samir said: This is my country. I was born in this country. My father was a librarian in this country for thirty-two years.

Amira said: I know.

Samir said: If we leave, they win.

Amira said: Who.

Samir did not answer. He did not know who they were. That was the worst part. There was nobody to fight, nobody to blame, no single moment of unambiguous hostility. There was only a series of perfectly reasonable decisions made by perfectly reasonable people, each one measured and proportionate and justified by circumstances. Howard Whitcomb was not a racist. Tom Bredon was not a bigot. Susan Delacroix was not a monster. They were all decent people doing what decent people do when they feel uneasy — creating distance, erecting boundaries, protecting the boundaries of the group from something that felt, to them, genuinely threatening. The fact that the threat was imaginary did not make their response any less real or any less devastating.

The Dean's meeting took place on the last Friday before Thanksgiving. Samir wore his best suit and brought his CV and his publications list and a letter from the American Association of University Professors. He sat in the Dean's office and listened to a series of sentences that all began with we value your contribution and all ended with but in the current climate. He nodded at the appropriate moments. He did not raise his voice. He walked out of the meeting and across the quad, past the library and the student centre and the bronze statue of the college's founder, a man who had made his fortune in the railroad business and donated a building in 1892. The sky was grey and low. The air smelled of wet leaves. He stood in the middle of the quad and thought about his father, who had believed that America was a place where a man could climb high enough to be safe. And he thought about Leila, who was eight years old and learning the violin and had asked if her daddy was a terrorist, and he understood that the ladder had never been as stable as he wanted to believe, that the height was an illusion, that the safety was conditional and always had been, that belonging was not a right but a privilege, and that privileges could be revoked by a committee vote.

He stood there for a long time. Nobody stopped to ask if he was all right. Nobody stopped at all.