Diyaa and Rana readied themselves to leave. The last residents of Qaraqosh were to report the next morning to the local medical center, to receive ‘‘checkups’’ before being deported from the Islamic State. Everyone knew the checkups were really body searches to prevent residents from taking valuables out of Qaraqosh. Before ISIS let residents go — if they let them go — it was very likely they would steal everything they had, as residents heard they had done elsewhere.

Diyaa and Rana called their families to let them know what was happening. ‘‘Take nothing with you,’’ her brothers told Diyaa. But Diyaa, as usual, didn’t listen. He stuffed Rana’s clothes with money, gold, passports and their identity papers. Although she was terrified of being caught — she could be beheaded for taking goods from the Islamic State — Rana didn’t protest; she didn’t dare. According to her brothers, Diyaa could be violent. (Diyaa’s brother Nimrod disputed this, just as he does Diyaa’s alleged cheapness.)

At 7 the next morning, Diyaa and Rana made the five-minute walk from their home to Qaraqosh Medical Center Branch No. 2, a yellow building with red-and-green trim next to the city’s only mosque. As the crowd gathered, Diyaa phoned both his family and hers. ‘‘We’re standing in front of the medical center right now,’’ he said, as his brother-in-law recalled it. ‘‘There are buses and cars here. Thank God, they’re going to let us go.’’

It was a searing day. Temperatures reach as high as 110 degrees on the Nineveh Plain in summer. By 9 a.m., ISIS had separated men from women. Seated in the crowd, the local ISIS emir, Saeed Abbas, surveyed the female prisoners. His eyes lit on Aida Hana Noah, 43, who was holding her 3-year-old daughter, Christina. Noah said she felt his gaze and gripped Christina closer. For two weeks, she’d been at home with her daughter and her husband, Khadr Azzou Abada, 65. He was blind, and Aida decided that the journey north would be too hard for him. So she sent her 25-year-old son with her three other children, who ranged in age from 10 to 13, to safety. She thought Christina too young to be without her mother.

ISIS scanned the separate groups of men and women. ‘‘You’’ and ‘‘you,’’ they pointed. Some of the captives realized what ISIS was doing, survivors told me later, dividing the young and healthy from the older and weak. One, Talal Abdul Ghani, placed a final call to his family before the fighters confiscated his phone. He had been publicly whipped for refusing to convert to Islam, as his sisters, who fled from other towns, later recounted. ‘‘Let me talk to everybody,’’ he wept. ‘‘I don’t think they’re letting me go.’’ It was the last time they heard from him.

No one was sure where either bus was going. As the jihadists directed the weaker and older to the first of two buses, one 49-year-old woman, Sahar, protested that she’d been separated from her husband, Adel. Although he was 61, he was healthy and strong and had been held back. One fighter reassured her, saying, ‘‘These others will follow.’’ Sahar, Aida and her blind husband, Khadr, boarded the first bus. The driver, a man they didn’t know, walked down the aisle. Without a word, he took Christina from her mother’s arms. ‘‘Please, in the name of God, give her back,’’ Aida pleaded. The driver carried Christina into the medical center. Then he returned without the child. As the people in the bus prayed to leave town, Aida kept begging for Christina. Finally, the driver went inside again. He came back empty-handed.