Since the fall of the Islamic State group’s attempted caliphate in Syria, hundreds of its prisoners have been freed.

Few were brutalised more by IS than Yazidis, a religious minority who were captured and enslaved when IS swept through their homeland in Sinjar, northern Iraq.

The UN says IS killed or enslaved thousands of Yazidis, and attempted to wipe them out – an act of genocide.

Men were murdered and buried in mass graves. Women were raped. Mothers and children were bought, sold and made to work as servants for IS fighters.

But some, like Nashaat, survived. After four years separated from his mother Fawzia, they're about to be reunited.