One morning in mid-January 2015, a small, furtive-looking man in a black hooded parka stood alone on the Turkish side of the Akçakale border crossing with Syria. 

The man glanced around uneasily, and finally approached a street sweeper in a blue jumpsuit. 'I want to cross to the other side,' he said. 'What can I do?' The street sweeper demanded 75 Turkish lira and pointed to a small hole in the fence, not far from the main gate. 

The man paid him but hesitated. He had come a long way, and was now barely 10 metres from his destination: the dusty brown hills of northern Syria, where the Islamic State began. 'What about the guards?' he said. 'No problem,' the street sweeper replied. 'Just go.' 

The man walked towards the hole in the gate. He bent down and squeezed through. On the other side, he began to run. One of the Turkish guards saw him and shouted. He did not stop.

 The newcomer's name was Abu Ali, 38, from Jordan. He had another name and another life, but like most migrants to the Islamic State, he had cast it off. He wanted to be born again.

Border crossing: One morning in mid-January 2015, Abu Ali, from Jordan, a small, furtive-looking man in a black hooded parka stood alone on the Turkish side of the Akçakale border crossing with Syria

Syrian crossing: These refugees are fleeing from Syria into Turkey but Abu Ali sneaked across the border in the opposite direction, paying a sweeper 75 Turkish lira to show him the way across

Sprinting to arms of Isis: Abu Ali bent down and squeezed through the border fence. On the other side, he began to run. One of the Turkish guards saw him and shouted but he did not stop until he reached Islamic State guards

 There were chickens in the garden out back, and the emir insisted that only the Americans and Europeans be allowed to slaughter them. It was training for killing infidels.

After an hour or so, a car appeared, and an Isis man drove Abu Ali to a reception house not far away. It was a large, one-storey building with a garden out back, and about a dozen other new arrivals were getting acclimatised.

'It was like an airport,' Abu Ali told me. 'I saw Americans, English, French, people from other countries – there was only one Syrian.' 

For the next five days, he slept on a mattress and talked endlessly with the other migrants, who mostly spoke English. The Isis officials told them they were investigating their backgrounds.

There were chickens in the garden out back, and the emir insisted that only the Americans and Europeans be allowed to slaughter them. It was training for killing infidels, he said.

At the end of five days, the new recruits were told it was time to leave. Abu Ali got into a minibus with about 15 others into the Bel'as mountains, a dry, craggy range of dun-coloured peaks to the east of the city of Homs.

Training: Abu Ali spent two weeks in a mountain training camp where they underwent lessons in Sharia law 

Indoctrination: He and 15 others were driven to the camp where they were fed a basic diet of cheese and bread

Harsh regime: The men would be woken up before dawn, then would perform the dawn prayer, before being taken outside for running and press-ups

Loyalty test: At the end of five days, the new recruits were driven into the Bel'as mountains, a dry, craggy range of dun-coloured peaks to the east of the city of Homs, for a training camp

For the next two weeks, all of the men would be woken up before dawn. They would perform the dawn prayer, then go outside for running and press-ups before the sharia lessons began at first light. The lessons were very basic, focusing on the difference between Muslims and non-Muslims, and the requirement to fight infidels and apostates.

 This was clearly some sort of loyalty test. Abu Ali felt their eyes on him, and he began to shake. He had been taught as a child that burning a man to death was forbidden in Islam. The images had sickened him. He heard himself say, 'May God help me.'

One night the emir in charge of the training course, a bald Syrian with pale skin who, in his previous life, had been a history teacher in Homs, said there was a special event in store. 

Once the men were all seated on the cave floor, the emir turned on the projector and a video flickered on the cave wall: an Arab man in an orange jumpsuit in a cage. Flames licked towards the cage, following a trail of petrol, and engulfed the man. 

A voiceover intoned that this was the Jordanian pilot Moaz al-Kasasbeh, who had been captured after his plane crashed. His grotesque execution by fire, in February 2015, was seizing the world's attention at that moment, and even some jihadis were denouncing it as an immoral act. 

The emir stood up and explained that this pilot had dropped bombs on Muslims, and his execution by fire was a just retribution under Islamic law. The men listened in silence.

Abu Ali soon sensed dozens of eyes turning in his direction. He was the only Jordanian there, and they all knew it. He had not said anything, but his horror at the video must have been visible on his face. The emir also stared at him. 

Depraved: Jordanian pilot Moaz al-Kasasbeh was captured and burned to death by Isis in February 2015 after his aeroplane crashed over Syria

Intense: The emir in charge of Abu Ali's Isis training played a horrifically graphic video of Jordanian pilot Moaz al-Kasasbeh, pictured above in the cage. The pilot was burned alive and the video was a test of loyalty for Abu Ali, who is also Jordanian

Silence: The horrific video of the pilot, above, which had been released worldwide, stunned the new recruits into silence in its depravity but Abu Ali could feel all eyes turning to him, because he was also Jordanian

Horror: As the video came to a close, Abu Ali heard himself shout 'May God help me' and the emir demanded to know why he had spoken those words, if he was horrified by what he had seen

This was clearly some sort of loyalty test. Abu Ali felt their eyes on him, and he began to shake. He had been taught as a child that burning a man to death was forbidden in Islam. The images had sickened him. He heard himself say, 'May God help me.' 

He and another recruit dragged wounded men from the battlefield. It was terrifying work. They could hear and feel bullets whizzing past them in the pre-dawn darkness, and some of the men they dragged – there were no stretchers – were screaming in pain.

Two Isis guards took him by the arms and led him out of the cave. The emir followed later. He sat down on the rocks with Abu Ali and asked him why he had spoken those words. Did he question what Isis had done? Abu Ali said no. He had only spoken out because people were provoking him. 

The emir seemed satisfied. 'At the beginning of this course you were a kafir (an unbeliever),' he said. 'Now you are becoming a Muslim.'

Abu Ali was intensely relieved. He had escaped punishment. But from that moment on, he told me, 'I began to suspect everything around me.' 

He had joined Isis in the hopes of getting a desk job and making himself into a good Muslim. 

In his previous life he had frequented bars and clubs and partied several nights a week, despite his wife’s constant haranguing. She was infertile, and the absence of children made their days especially empty.

By 2012 his father’s government work had stopped after the rebel Free Syrian Army entered Aleppo and his profligate life began tilting towards despair. 

He was living off handouts from other family members abroad. Abu Ali declared that he was divorcing his wife. In Islamic law, that’s all it takes. She moved out.

After that, Abu Ali felt he had nothing left to lose.  

Reluctant figher: Abu Ali was transferred to the Garma district of Anbar province, west of the Iraqi capital Baghdad, where he was ordered to act as a medic, rescuing desperately wounded fighters 

Battle scarred: Abu Ali refused to fight further because he was convinced the battle could not be won. He told his commander: 'We don't want to fight any more. You are leaving dead and wounded men behind. The prophet Muhammad, peace be upon him, did not force men to fight against their will'

The tale of Abu Ali's life as a jihadi is published in autumn

When the two-week sharia course was over, most of the men were transported to another group of damp mountain caves a few miles away. They now started the military training class. Abu Ali, with his smoker's lungs, would just sit down on the rocks when he got tired. 

The trainers shouted at him, and he would hold up his hand and shout back: 'I'm doing administration, not combat.' He was already getting a reputation as a laggard.

On the last day of the course, the men were summoned from their cave in the morning and asked to recite an oath of loyalty. Abu Ali found himself standing with about three dozen other men near a bus. 

A Syrian commander in battle fatigues told them they were going to the frontlines in Iraq. 'Sir, I don't want to go to the frontline,' Abu Ali told the commander. 'They said I could do administration in Raqqa.' 

The commander looked at him, stone-faced. 'You swore an oath,' he said. 'You must listen and obey now. The penalty could be death.' Abu Ali stood for a moment, registering the shock, then he walked towards the bus.

After a few days of travel, Abu Ali arrived in Garma, a village just west of Baghdad near the frontline.

He and another recruit dragged wounded men from the battlefield. It was terrifying work. They could hear and feel bullets whizzing past them in the pre-dawn darkness, and some of the men they dragged – there were no stretchers – were screaming in pain.  

On the morning of the third day, Abu Ali and a new friend named Abu Hassan walked together into the headquarters in Garma and confronted the Iraqi commander. 

'We don't want to fight any more. You are leaving dead and wounded men behind. 

'The prophet Muhammad, peace be upon him, did not force men to fight against their will.' He knew he was taking a risk.

Abu Ali was packed on to a bus bound for Syria. The men on board knew they were likely to be punished.  

Freedom, finally: When Abu Ali was moved to Tel Abyad he found himself next to an internet cafe and his WhatsApp messages pinged into life

Arriving back in Raqqa, they were taken to a soccer stadium, known as Point 11: a notorious Isis prison and security centre. 

A man arrived and addressed them. 'Brothers, do not say, 'I will not fight any more.' Just say, 'I prefer to fight in Syria.' You will be given one more chance.'

A few days later, Abu Ali found himself alone in a house in the town of Manbij, not far from the front. There was an internet cafe next door, and to his delight, he heard the chime of a WhatsApp message on his phone. He looked at it and his heart leapt: it was his wife. 

She had written an old expression that they both liked: 'If you love something, let it go. If it doesn't come back, it wasn't meant for you. But if it does, it will be yours forever.' 

Abu Ali found himself shaking with emotion. He apologised for his mistakes. He told her he wanted to come back.

Abu Ali said: 'The second I saw her first message I started hating them all. I said to myself: What have I done?'

He had heard a rumour that one of his comrades in the Iraq battle, a man from Morocco, had escaped to Turkey. He sent him a WhatsApp message.  

Escape: Amid the chaos of the border town of Tal Abyad, where refugees fled into Turkey to escape the fighting, above, Abu Ali managed to make contact with a smuggling gang who spirited him to freedom

Syrian civilians leave the town of Tel Abyad seeking refuge in the Turkish border town of Akcakale, where Abu Ali first crossed into Syria and where he later escaped 

The Moroccan wrote back quickly. He said: 'Go to Raqqa'. Equipped with a sick-leave document, Abu Ali got on a civilian bus early the next morning. He was wearing an Afghan-style cloak that identified him as a member of Isis, and no one gave him any trouble.

By the time he arrived in Tal Abyad it was 9pm, well past dark. He found an internet cafe and went inside to wait for the next message. As he looked around, it became clear that everyone in the cafe was Isis: long beards, AKs on the shoulders, Afghan robes. 

Abu Ali felt himself shaking. He tried not to look at anyone, but one man was eyeing him suspiciously. The meeting time came and went. It was almost 11pm, and the cafe would soon be closing. He said to himself: that's it, I'm done for.

Abu Ali crawled through a hole in the border fence to freedom on the night of 25 May 2015, just over four months after he had entered Isis territory.

Finally, just before 11pm, two motorcycles pulled up just outside, and one of the riders shouted through the cafe door at Abu Ali: 'The food's ready, sorry we're late.' Abu Ali got up to go. 

As he did so, the Isis man who had been staring at him in the cafe stepped forward. 'Where are you from?' he said. 

Abu Ali replied in an Aleppo accent – he figured a local by himself was less suspicious than a foreigner: 'I'm sorry, I'm late, I have to go.' 

He walked out the door and got on the back of one of the motorcycles, scarcely breathing. But the bike took off down the road and no one followed. 

The next day, after a sleepless night in a nearby house, the men who had rescued him from the cafe accompanied him to a remote stretch on the border. 

Abu Ali crawled through a hole in the border fence to freedom on the night of 25 May 2015, just over four months after he had entered Isis territory.  

Culled from Mail Online