MELBOURNE, Australia — Karen Nettleton has spent the past five years in search of her grandchildren, who were taken by their mother in 2014 from Sydney, Australia, to join the Islamic State in Syria. Finally, in late March, she made it to the sprawling al-Hawl refugee camp in Syria’s Kurdish northeast.

There, she found a teenager she believed to be her granddaughter. As she lifted a niqab to reveal the face of the girl she was holding in her arms, Ms. Nettleton wailed.

She clung to her granddaughter, Hoda Sharrouf, 16, who sobbed and told her she was certain she was dreaming. Ms. Nettleton promised her she was not. “You’re not going to wake up,” she said in footage broadcast on Monday by the Australian show “Four Corners,” whose crew had accompanied Ms. Nettleton to the camp.

More than 200 Australian citizens have left the country to join the Islamic State, 70 of them minors, according to a 2018 report from the International Center for the Study of Radicalization at King’s College London. While many were killed during the war, dozens are thought to remain in Syria’s refugee camps.