Ahmad and her colleagues have been working meanwhile to develop, with considerable quiet success, a criminal-justice alternative to Guantánamo. It’s a high-wire act. The public has unique expectations of law enforcement with respect to terrorism. “When there’s a bank robbery, we try to solve the crime,” Ahmad said. “But nobody thinks our job is to stamp out bank robbery. Terrorism is different. People expect us to prevent it.” Many terror cases are difficult to make, with the strongest evidence often classified or inadmissible. “And we can’t afford to lose,” Ahmad told me. “We can’t get anything wrong. If we lost a major extraterritorial case, there might never be another chance.”

Ahmad had a multifaceted upbringing. She grew up in suburban Nassau County, Long Island, with her father and stepmother and two younger brothers, and she also lived part time with her mother, in Manhattan. Her parents had divorced, amicably, when she was an infant, and, as Zainab grew, according to her father, Naeem, “she would play Mom off against Dad, but always for one thing—to buy more books.” Her parents were part of the Pakistani diaspora, and Zainab spent summers in Pakistan and England. Visits to Pakistan were an adventure—she had dashing, rowdy cousins—but England was often a shock. “You could feel the discrimination,” she told me. “My cousins, no matter how successful or well educated, were never going to be accepted as British. People would ask me where I was from. I’d say I was American. Then they’d say, ‘Yes, but where are you really from?’ I was always so glad to get home.”

“We felt comfortable here,” Naeem told me, when I visited him and his wife, Nasrin, at their home, in East Meadow. “I felt comfortable with my neighbors, and never told my children to avoid kids because they’re Christian, Jewish—none of that.” (Most of Zainab’s friends as a child were Jewish.) Naeem, a retired engineer, is an active member of a local mosque, and has taught Sunday school since the nineteen-eighties. “I am a very religious man,” he said. “But not a religiosity man. I don’t care what other people do.”

Naeem and his first wife, Jamile, left Pakistan for Canada in the nineteen-seventies—for economic reasons, he said. But his engineering degree, from the University of Peshawar, was not recognized in Canada, so he found work investigating insurance claims. In 1977, the couple moved to New York, where Zainab was born three years later. Naeem managed a restaurant in midtown and later helped run a construction firm. His boss, who eventually became his partner, was a Hindu from India. “We’re both from the Punjab,” Naeem said. “But if there was a war between India and Pakistan we didn’t bring it home. We were the same, except he went to temple and I went to mosque.”

Zainab’s parents describe her as a cheerful, precocious child. “She never walked, she always skipped,” Jamile, who now lives in Pakistan, told me. “Her sixth-grade teacher praised her respectfulness, and that meant a lot to me. A lot. It’s difficult to raise a respectful child in the U.S.” When Zainab was eight or nine, she and Naeem read the entire Quran together, which took about a year. She didn’t understand a word, she said. Later, as an undergraduate at Cornell, majoring in health policy, she studied Arabic. “We talked every night,” Naeem said. “She would give me the gist of the Arabic. I would send her back to class with new ideas and questions.” Even as a lawyer, he said, “she sometimes uses me as a bounce-off for ideas—to see what I say.”

Naeem served lunch and tea. A few days earlier—this was last spring—there had been a Trump campaign rally in Bethpage, a couple of miles to the east. “You could hear the roaring from here,” Naeem said. “Everything but the ‘_Build the wall! _’s.” Like his daughter, Naeem has a quick tongue and a ready laugh.

Nasrin, a tall, smiling woman in her fifties, is the town clerk of Hempstead, which has a population of eight hundred thousand. She is the first elected official of South Asian extraction in New York State. While we talked, white guys in pickups parked in the driveway and came to the front door, where they conferred with Nasrin over sheaves of documents—constituent service on a rainy Saturday afternoon. The American Dream lives on Long Island.

And yet I remembered Zainab saying, “If I were fifteen now, growing up where I did—I don’t know. Everything’s changed.” She meant the level of mistrust that Muslims in America face. “When I was a kid, even though I had a funny name, and didn’t look like everyone else, it honestly took me a very long time to realize that. There was nothing that made me feel different. Substitute teachers would come, and start to take attendance, and hesitate, because my name was at the top of the class list, Ahmad. They’d say, ‘I know I’m going to pronounce this wrong.’ And the whole class would be, like, ‘Zainab. Duh.’

“Every year, in elementary school, we’d have American Heritage Day. Everybody would say where their family was from. Germany. Poland. I remember, in second grade, saying, ‘My family’s from Pakistan.’ The teacher pulled down a map, and I didn’t know where Pakistan was, even though I’d been there. I was totally embarrassed. But then I was relieved because the teacher didn’t know, either.” Ahmad laughed. “I’d kind of like to go back to a time in America when teachers didn’t know where Pakistan is.”

Jamile told me, “When Zainab was little, she wanted to be a receptionist. She loved answering the phone. Then she wanted to be a nurse. I mentioned lawyer, because my dad was a lawyer, but I wasn’t serious.” Ahmad herself is vague about how law happened. She had planned to be a hospital administrator, but things went sideways after the September 11th attacks, and she ended up at Columbia Law School, on a full scholarship. One judge she clerked for, Reena Raggi, of the Second Circuit Court of Appeals, recalls her strong academic background in finance and economics. “She excelled in a variety of areas,” Raggi told me. “Her ability to analogize. Her aptitude for solving problems. She has a deep critical mind. Zainab doesn’t come across as a hardboiled, aggressive prosecutor. She’s reserved—that’s her upbringing. She would have been successful in any field. But, I must admit, I didn’t see this coming.”

Naeem once got a call from his daughter while she was clerking for U.S. District Judge Jack B. Weinstein. It was 2006, at the end of a major Mafia trial. “Zainab was crying,” he said. “The defendant had been convicted. She said, ‘I couldn’t take it when he took off his watch and his necklace and gave them to his family.’ She had got to know these people. So I said, ‘Which side would you rather be on, the government or the defense? You’re not after the person, you’re after the truth.’ ”

When Ahmad joined the Eastern District, in 2008, she first worked on Brooklyn and Staten Island gang cases, but soon found herself drafted into a terrorism investigation that centered on a plot to blow up fuel tanks and pipelines at John F. Kennedy International Airport. The plotters, one of them a former baggage handler, were a motley quartet from Guyana and Trinidad, and the case led to both Iran and Al Qaeda. “You start following a disgruntled baggage handler, a guy who’s mouthing off in Queens,” Ahmad said. “But he has the potential to connect with serious networks—and this guy did it.” Russell Defreitas, the baggage handler, made trips to Guyana, looking to contact a senior Al Qaeda leader. When his search failed, he settled instead for Abdul Kadir, a chemical engineer and former member of Guyana’s parliament, who had transferred his allegiance to Islamist extremists in Iran. The investigators moved carefully, placing an informant with Defreitas, but not, at first, asking him to gather evidence with a tape recorder. “We weren’t sure about Guyana law, or the Guyanese, and you don’t want to blow your informant,” Ahmad said. “We’re not the intelligence community. We’re law enforcement. We have to declare we’re there. You have to figure out who you can trust. Eventually, we worked it out, and we got him recorded.”