Families who have escaped from the Islamic State stronghold of Raqqa have told Sky News they witnessed militants carry out countless public amputations, some of them against children.
One mother spoke of her anguish at being pressured into "selling" her 14-year-old daughter in marriage to an Egyptian IS fighter who was 29.
There are growing signs of tension among the fundamentalists in the city - and an increase in people attempting to flee.
There are reports too that IS fighters are building tunnels in expectation of a tremendous battle to try to retake the Syrian city.
We spoke to two families just over the Syrian border in Turkey, who both chose to remain anonymous because of a lingering fear of being tracked down by IS - or revenge being taken on their remaining family members inside Raqqa.
The mother of the teenager who was to be sold to the IS militant was alone, bringing up her four sons and daughter after her husband was killed in an airstrike.
She feared disobeying the IS fighters but admitted being tempted by the $500 worth of gold he offered in return for her daughter.
Both mother and daughter cry as she tells us: "My daughter said, 'My mother, do you think if my father was alive, he would accept this marriage?'"
The little girl says: "He told me to carry a weapon and to stay with them. I told him, 'please I want to leave now"."
Her mother interrupts her to say: "She is a baby. How can they let her carry a weapon?
"At her age, she should be in the ninth grade. She is still playing on the swings with her little friends. She's not interested in guns.
"When you enter their areas, it is terrifying: you see ammunition and weapons."
The family managed to escape before the marriage went ahead, with the mother using the money given to her by the IS fighter to escape to Turkey.
The other family huddle on a sofa together, the three young children squirming with boredom as they listen to their mother tell us they saw countless public amputations.
"All my children have seen them," she said.
One of those being punished was a young 11-year-old boy who was their neighbour. They knew him, used to play with him.
The mother tells us he was alone, an orphan and was trying to sell a stolen car battery for food.
The man he tried to sell it to informed the IS authorities and he was publicly tied down, his arm chopped off.
''They used a sword… they put a block of wood underneath his hand, put his hand on it and said this stole a car battery … they didn't say he was an orphan.
"They said this hand has stolen and he had to be punished and they cut his hand off. We know him, he was our neighbour and he was an orphan."
The children now have nightmares and find it hard to sleep. Their father is sitting grim-faced at one end of the sofa.
He was on his way to Damascus more than three years ago to try to sort out paperwork, so he could take the family out of the country to escape what he felt then was a deteriorating situation in Raqqa.
He was stopped and arrested when they mistook him for another person.
He was held by the intelligence agents for seven months and tortured but refused to confess. They threw him in jail and he was basically forgotten.
The man was finally freed last month when the authorities said they'd traced the person they were looking for.
He emerged into a Raqqa which was in the grip of IS - an utterly changed city.
"Everything has changed," he says.
"The people have changed. Their hearts are like stones. The city has changed. The houses were on the ground … destroyed."
Despite the risk of death if caught, the couple and their three young children paid smugglers and spent 20 days travelling across the country and frontline to get into Turkey.
The father said: "I can't live in Raqqa. what I saw in Raqqa during the 15 days I lived there (after prison) was like I'd escaped from death, to find death in front of me again."
