Sky News' Mark Stone meets Islamic State prisoners inside a Syrian prison where inmates recently tried to escape.
"You must not film anything outside the prison," the guard warns us as we arrive.
A few weeks earlier, there had been an attempted prison break. Hundreds of Islamic State (IS) inmates tried to escape, prompted by the chaos of a car bomb outside.
It was not successful. But the Kurdish soldiers guarding this prison can give no guarantees that it will not happen again.
"It is a ticking time bomb waiting to explode," the soldier in charge of the prison then warns.
We are inside one of a number of IS prisons in northeastern Syria . This is where the men of the Islamic State, of fighting age, are held.
They were brought here after their so-called caliphate fell in March. And then they were forgotten.
They ask: "What's going to happen to us?" It is a question they ask over and over.
"Will our governments take us back? Why are we getting no information?"
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Of the many things to hit you when you walk inside, the silence is one. It is mid-afternoon but with a power cut the place is in darkness.
A guard opens a series of huge steel gates partitioning a long corridor. One of the gates has newly soldered brackets. In the attempted prison break, the inmates had ripped it clean off the wall.
Beyond the gates, behind the walls, in cells to the left and right, are thousands of IS prisoners. On each door is the number of prisoners behind it.
Most of the cells, which are not large, contain more than a hundred men from all over the world. Dressed in orange boiler suits, they wait, while their countries wonder what to do with them.
The first inmate we speak to introduces himself as Mohammed Diemer, from Germany.
"For me it was a mistake. For me, I watched too much propaganda. I fell into their tricks, you know," he tells me. He looks like a broken man.
"What are their tricks?" I ask him.
"They make good propaganda. There were some people, they made, called me to here and told me you can live here. Islamic... and... in the end it wasn't," he says.
"It wasn't what was expected."
Does his family know he is alive?
"I think so. I told them I was going to go out. I told them also to talk to the embassy.
"I don't know what is happening. I spent eight months here. No news, no nothing. It's a very hard time. Very hard."
In the cell opposite him we meet Zachariah Masrif who says he is an intensive care doctor from the Syrian city of Homs.
Like many others have done, he claims that he was simply caught up in the wrong place when IS took over. And as a doctor, his skills were needed.
His defence, if he is ever able to present it, is that he and others were duped and then trapped.
"The Syrian people, sir, you know them, they are clean people, they are simple people," he tells me.
"These [IS] people who came from Iraq and they came from outside; they used our clean hearts and they put their 'come fight for Islam, Islam, Islam, Islam, Islam', they pull all of these people, women and men and youths, and they pull them and especially they are working on the teenagers - from 14 to 16 to 20 - these are the people they were targeting."
We are taken to the prison clinic. This is where the war wounded are kept. Some are horribly disfigured. I watch one man bandaging the stump of his amputated leg. Another stares me out as I look at him. It is deeply unsettling.
Among them we meet Ishak Mostefaoui, from Leyton, east London.
"I was within the Islamic State, living under the Islamic State, yeah," he tells me casually.
At your own choice?
Again, he seems nonplussed. Does he still believe in the Islamic State?
"Well now it's over. It's over and done with and we're here... hoping to go back to what we done before and we have been here for the last nine months not knowing about our families."
But does he believe in what IS stands for?
"No, no, no. They have done a lot of mistakes and you know life is a lesson curve, a learning curve like we say.
"They cut people's heads off in Raqqa," I remind him.
"Yeah, I'm telling you..."
Was he involved in that at all?
"No, no, no. I was not involved in that. We condemn all the crimes and oppression that they actually did then," he insists.
Should we believe him, or not?
That is a judgement no one is making. Instead, governments globally pretend they are not here.
In a control room, a single Kurdish guard watches a bank of CCTV screens. Each camera is trained on a cell with dozens inside.
The guard points out the two cells with those he considers to be the most dangerous inside.
And then the stark warning: "We established this prison according to our abilities and circumstances. This is the best we can do without anyone else."
He says that the recent incursion by Turkey into this part of Syria has made matters even worse.
"After Turkey's attack against our borders and our people, part of our forces here withdrew and we're forced to go to defend and protect our borders, territory, homes and families," he says.
"Half of the forces left. This made our security level less than before."
There are no easy answers for all this. Every option is bad. To take them back and attempt to prosecute? Or to leave them? Are they all perpetrators or are some victims, duped by the cult?
Maybe some are victims who became perpetrators. They are questions that, for now, no one is even trying to answer.