Western intelligence agencies believe Tunisians head the league table of foreign fighters swelling ISIS ranks, and Tunisian authorities identify the town of Kasserine as a veritable pipeline of recruits.
Once famous for its central role in the Tunisian revolution, Kasserine is now infamous as a source of radicalized young men flocking to Syria and Libya in their thousands.
So why? Why here?
Just 30 km (18 miles) from Tunisia's border with Algeria, Kasserine's geography makes it ideal as a meeting point for jihadis from both countries. And the ridges and crevices of the Chaambi Mountains provide perfect cover for terrorist training camps, in spite of the government's ongoing efforts to uproot them.
In the poor Kasserine neighborhood of Al Zuhour, one road is described to us by a local drily as "Avenue de Jihad" because, he says, of the sheer number of families whose sons are either missing, dead or in jail.
The first thing that hits you is the number of young men hanging around in the middle of the day with nothing to do. As we pull out our cameras some of them start to show us their scars. They say the wounds are mementos of the running battles waged with the security forces of former dictator Zine el Abidine Ben Ali, who led Tunisia for 23 years before being ousted in 2011.
They had fought for a better life but in the post-revolution chaos, bitter poverty and unemployment have made Kasserine a fertile recruiting ground.
'They taught me how to pray'
In one of the houses, a young man agrees to speak to us as long as we conceal his identity. Silhouetted against an open door, nervously he begins to speak.
"I used to drink and smoke, I decided to find my way to my neighborhood mosque. Find my way to God.
"That's when I met them. They taught me how to pray. "
"They," would turn out to be ISIS militants but the young man claims he didn't know that at the time. He says all he knew was that he was searching for answers and they had those in ready supply.
"I saw they had their own private little groups and I joined their discussions. They talked about how you could attain heaven, what our duties were as Muslims."
What he is describing echoes much of what we've heard elsewhere in Kasserine. While jihadi recruitment in the West happens mainly online, here recruiters operate openly through the local neighborhood mosques.
After the deadly attack on tourists in the resort of Sousse, Tunisia's government announced a ban on what it called 80 "illegal mosques" nationwide.
'Be killed, or be a killer'
For our interviewee, it all came to a head in the early hours of one morning: As the usual group gathered for dawn prayers, the police raided the mosque.
It was, he says, a reality check.
"I stopped going to the mosque, I even stopped praying. Then the police accused us of praying with terrorists, of consorting with them. I spent three days in jail here and three days in Tunis. After that, when they released me, I just stayed home."
But his new friends weren't done with him.
Earlier this year he says threats began arriving on Facebook. It was the men from the mosque. They told him they knew where he lived. His sin? He hadn't joined them.
"He said to me 'you, I know your mother, your fathers, I live nearby. I can take your brother, your mother. I can throw a bomb over your wall.'"
Terrified, he says he agreed to meet the militants. They arranged to meet in town where a man describing himself as an ISIS commander told him; "we have a job for you."
"I knew then," the young man told us, "I was either going to be killed or be a killer."
It was after that meeting that he was picked up for a second time by police and interrogated again. They told him, he says, that they would protect him from ISIS — but he's not convinced.
"The patrol maybe passes by the first day, maybe even the second and third but are they going to sleep by my side?"
"Can they stop a bomb thrown over my wall? Here, these guys, they can come and go as they please. No one is safe."
