After five years, countless phone calls, online messages and two failed rescue missions, Sydney grandmother Karen Nettleton has been reunited with her three surviving grandchildren and two great-grandchildren in a refugee camp in north-east Syria.

Key points: It is the first time Karen Nettleton has seen her grandchildren since they were taken to Syria

It is the first time Karen Nettleton has seen her grandchildren since they were taken to Syria Ms Nettleton is desperate to bring them back to Australia

Ms Nettleton is desperate to bring them back to Australia The Federal Government has told Ms Nettleton the children will soon be released into her care

It is the first time she has seen Zaynab, Hoda and Humzeh Sharrouf since they were taken by their mother Tara Nettleton, wife of notorious Islamic State (IS) fighter Khaled Sharrouf — to join the terrorist organisation in Syria and Iraq. Tara, Khaled and their two eldest sons have all since died.

Four Corners accompanied Ms Nettleton as she made the desperate journey to Syria to rescue the three orphans and Zaynab's two toddlers, Aiesha and Fatimah, from the al-Hawl refugee camp, where they have been living in squalid conditions for several weeks after they managed to escape Baghouz — IS's final stronghold.

"I can't believe this is happening. I can't believe I'm here with you, I'm pretty sure I'm dreaming," 16-year-old Hoda said as she pushed her face into her grandmother's chest.

"You're not dreaming, you're not going to wake up," Ms Nettleton replied as she kissed Hoda repeatedly.

The beginning of the nightmare

Karen Nettleton had not seen her grandchildren since they were taken to Syria to join Islamic State. ( Supplied )

For half a decade, Ms Nettleton has lived alone in her silent house in suburban Sydney, the only physical reminder of her family the dozens of photos that hang in almost every room.

In February 2014, Ms Nettleton, Tara and the Sharrouf children went to Malaysia on a holiday. Tara told her mother she planned to go on to Turkey.

She said she wanted to visit the famous Topkapi Palace in Istanbul, where scenes from her favourite Turkish soap opera were filmed. They would be home in a few months, she told her mother.

"I kissed the kids, kissed their faces. Hugged them, kissed them again. Hugged Tara. Kissed her. And walked out. And left them there. But I didn't know I was saying goodbye to Tara, to Abdullah and to Zarqawi when I did that. If I knew, I don't know if I would have gone," Ms Nettleton said.

It was the beginning of a nightmare from which Ms Nettleton only awoke this month.

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Karen, Hoda and Zaynab before they left Australia. ( Supplied )

Since 2015, the ABC has chronicled Ms Nettleton's ordeal as she has tried to locate her missing grandchildren and bring them home from war-torn Syria.

Ms Nettleton managed to stay in touch with the five children mainly via messaging apps. She also communicated with Tara up until September 2015, when the 31-year-old died of intestinal problems.

Twice Ms Nettleton flew to Turkey to try to arrange her family's safe passage out of the war zone: twice she came home, defeated, to her silent house.

"I need to have my children back. They deserve to come back here. They deserve to be here and happy and safe and have food and be able to walk down the street, be normal," Ms Nettleton said.

A phone call that changes everything

Two of Karen Nettleton's grandchildren, Abdullah and Zarqawi, were killed in a drone strike in Syria. ( Supplied )

Then in March, Ms Nettleton, 58, took the call for which she had waited five years.

"Friday night I [got] a phone call from Hoda telling me she's in the refugee camp, al-Hawl refugee camp. I could not believe it," she said.

Two days later, Zaynab, Zaynab's two toddlers and Humzeh also arrived at the camp.

"And then to get the call from Zaynab … it took a couple of days for Zaynab because she had to be processed, but getting her call was … being told she was there, to actually hear her voice. I just knew they were all safe, they will all be together," Ms Nettleton said.

Once again, Ms Nettleton packed her bags and jumped on a plane for the Middle East. This time she flew into Erbil, Iraq, and made the dangerous journey over the border into Syria and to the al-Hawl refugee camp. Four Corners travelled with her.

The final search

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For 45 minutes, she walked the muddy paths of the camp of more than 72,000 people. She weaved between hundreds of sad, tumble-down tents yelling her granddaughters' names at the top of her voice.

She spoke to dozens of women wearing the all-covering black female gown and veil demanded by IS, asking if they had seen her children.

Eventually, a slight British woman told her the Australian section of the camp was at the camp's far corner. Ms Nettleton started walking.

"Humzeh! Oh, baby!" she cried as she spotted the grandson she hadn't seen for five years. She ran to him, picked him up, swung him about and kissed him across his face.

Humzeh, who was four when he left Sydney and by now has spent more time living in Syria than he has in Australia, led Ms Nettleton over a slight rise and to the family's tent.

Humzeh Sharrouf at the al-Hawl refugee camp. ( ABC News: David Maguire )

As Hoda emerged from the tent, she was so stunned to see her grandmother that her hands visibly trembled.

Hoda and Ms Nettleton were both wearing black and as they fell into each other's arms in a deep embrace, it almost seemed like they were one person.

"Oh my baby, I missed you so much," Ms Nettleton cried as she held her granddaughter.

About half-an-hour later, Zaynab arrived, and the tearful, joyous, reunion was repeated.

"I told you I'd come, I told you I'd come," Ms Nettleton laughed as Zaynab wept and fell into her grandmother's arms.

The family went inside the tent. Ms Nettleton dragged in a maroon suitcase bursting with gifts — the girls' favourite chocolates from Australia, dolls for the toddlers, a headlamp for Humzeh, as well as food, medical supplies and clothes.

The family stayed together for hours, hugging and talking about their past five years and their future — they hope to return to Australia.

After five years of silence, Karen Nettleton's life was suddenly a riot of sound and movement.

Australian officials have told Ms Nettleton her children will soon be released from al-Hawl into her care so they can return to Australia, though it is unclear how long their final journey will take.