Thirty-four Yazidis escaping from captivity under Isis have made it to freedom in a new Channel 4 documentary called Escape from Isis. The documentary follows an underground network working to free women and children who were captured and kept as slaves by the terrorist group in Iraq.

The group spent two days walking through Syria and Iraq to safety after spending eight months as sex slaves. Many of those rescued had been subjected to rape, sexual abuse and violence by Isis militants.

According to the Daily Mail, the rescue mission by resistance fighters was organised by local lawyer Khaleel al-Dakhi.

The documentary's director told the Daily Mail that many of those rescued were Yazidis who had been treated as "subhuman" by Isis fighters, who believe they were "devil worshippers". The terrorist organisation has systematically targeted Yazidi girls and women through sexual violence. Last August, over 3,000 girls were kidnapped from their homes by Isis in northern Iraq.

"They're desperate to get their hands on a mobile phone and when they do they call their families and tell them 'I'm alive'," Watts said of the kidnapped girls. Once the victim's family members are notified, the resistance network works to rescue them.

"They have all sorts of different ways of doing it, but they have a network of guys insides Isis [territory]," Watts told the Daily Mail. "They identify where the girls are being held, go in and grab the girls and take them across the frontline."

The resistance group has rescued nearly 500 women, but have lost rescuers in the process, Watts said. The director recalled a recent incident in which Isis fighters set up a trap for two of the resistance workers.

Watts said, "They got a woman under duress to call up and say, 'I'm in this house can you come and rescue me, the guy holding me is away', when in fact it was a trap...These two guys turned up, Isis caught them and they were stoned to death."

Channel 4's Escape from Isis airs on 15 July at 10pm in the UK and on 14 July at 10pm on PBS and online in the US.