Sometimes one comes across a situation which redefines the notion of what it is to be human in a truly terrible way.

So it is with the conduct of so-called Islamic State (IS) in its would-be jihadist utopia known as the “caliphate”.

I have just emerged, blinking into the light, from editing a film about the rape and abuse of Yazidi women slaves, filmed by my colleague Mehran Bozorgnia.

So shocking is it that whenever I try to talk about it at any length, my eyes well up with tears. Others watching it have reported the same.

Last year some 300, 000 Yazidis fled the lightning advance of IS fighters across Iraq. Some of them sought refuge on Sinjar mountain, where last August we filmed Iraqi helicopters trying to rescue as many as they could. Yazidis crushed one another in a desperate stampede to escape.

Untold numbers died on that mountain in unbearable heat. Western policymakers, reluctant to be sucked back in to Iraq, sent air drops of food and water but judged an international humanitarian airlift unnecessary.

But the inhabitants of the village of Kucho failed to get away in time. The film we have made documents what happened to the women who were trapped behind the IS front line that August.

An excellent Amnesty International report, published in December, reckons that some 300 of those abducted by IS, mostly women and children, have managed to escape, but that “possibly thousands” are still in captivity.

A group of women refugees has shown remarkable bravery in talking on camera to Channel 4 News about their ordeal. Some of them have been made pregnant by the IS fighters who bought them at auction and carted them off to the IS de facto capital of Raqqa in Syria, where they were frequently traded as sex slaves between the men.

Some women are known to have committed suicide in captivity. One woman, 19-year-old Hakimeh Jelo, told us that being forced to convert to Islam shamed and outraged her more than being sold.

“We were asking them to kill us,” she says. “We were pulling their guns towards our heads, but they refused.”

Jalileh Amo, who is 30, told us that women would have their arms broken or skulls cracked if they refused to comply. When the women got better, they would be sold and abused again. Girls as young as eight or nin were sold. Brief “marriage” services entitled IS fighters to take the women alongside their existing wives.

To quote one IS document on Yazidis: “One should remember that enslaving the families of the kuffar (infidels) and taking their women as concubines is a firmly established aspect of the Sharia”.

There’s also an IS “office of religious edicts” which claims: “If she is a virgin, he can have intercourse with her immediately after taking possession of her… it is permissible to buy, sell or give as a gift female captives and slaves, for they are merely property, which can be disposed of…

“It is permissible to have intercourse with the female slave who hasn’t reached puberty if she is fit for intercourse; however, if she is not fit for intercourse, then it is enough to enjoy her without intercourse”.

The brutality and misogyny these women and girls have endured is beyond words. Psychological counselling is virtually non-existent.

And a Yazidi religious leader makes clear in the film that, although the women will be welcomed back into society, their as yet unborn babies will not.

Many of the women have scores of relatives missing and presumed dead. Hundreds of their menfolk from Kucho village were lined up and shot. Survivors, who hid under piles of bodies, have lived to tell the story.

The women escaped thanks to the kindness of individuals, including Muslim women in the households where they were kept. They waited for their IS male captors to leave for the front line and reached out to a Yazidi rescue network via the internet or through sending texts on mobile phones.

There is no going back to Kucho. It is surrounded by Arab villages, which stand accused by refugees of colluding in kidnap and murder. The women we have spoken to want to go to Europe or America.

And with the fate of Iraq’s Yazidi minority, so may go Iraq itself: a nation torn apart by sectarian hatred, unless the atrocities now perpetrated by Islamic State can bring the country to its senses.

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