Warning: Disturbing content
Mohammed is giddy with excitement as he films the discovery of three IS fighters on his mobile phone.
鈥淪hoot him,鈥 he shouts, gesturing at one of them.
His nervousness gives him away as the unit鈥檚 cook. He鈥檚 unarmed, but his fellow soldiers from the Iraqi police special forces - known as the Emergency Response Division - are armed to the teeth and are not taking any chances.
Two of the IS fighters are clearly dead. One, most likely a boy, is buried under the rubble of concrete bunker. His small, blackened hand sticks out from mangled remains. Nearby, an older fighter lies in the grass. His eyes are open, but part of his head is missing. He died in the same airstrike that took out the bunker.
But it is the third man, lying in the shadows, further ahead on the path alongside the River Tigris, who has the soldiers worried.
They fire a couple of shots into the prone figure. It does not move.
鈥淗e is a son of a bitch, he was hiding. Be careful, be careful,鈥 says one of the soldiers. 鈥淚 don鈥檛 think he has a suicide vest,鈥 says another.
They are at the foot of an olive grove, which is serving as the temporary base of the ERD as they push towards west Mosul, the last major redoubt of IS in Iraq.
Up close I look upon the dead man. His right leg is mangled, sliced through to the bone. He appears to have crawled out of the bunker and found a small hiding place in the rocks by the riverside.
Even in death his face is distinctive - a narrow chin and a puckish nose. His beard is wispy. He is more of a boy than a man. Nearby, soldiers find an M16 rifle which is marked as property of the US Government.
It is likely to have been among the thousands of weapons and vehicles IS seized from retreating Iraqi forces when it swept through from Syria more than two years previously.
鈥淎del, Adel, does anyone have ammunition? I want a full magazine,鈥 says a fighter searching the dead man. The M16 now belongs to the man who found it.
鈥淲e have to go, it isn鈥檛 safe here,鈥 an officer tells me. The men are jumpy and want to return to the base. There are still other IS fighters in the area, they warn.
It is late February and these men are in the midst of the battle of their lives. In three days they made lightning progress across the territory to the south of Mosul. Ahead of them the village of the Al-Buseif, then the ruined airport and the neighbourhoods of the west of the city.
All would fall in rapid succession, but the closer to Mosul they come, the more IS fighters they encounter, and the more bodies end up strewn across the roads and pathways.
It is already clear from the assault on the city鈥檚 east - it took 100 days - that IS prepared well for this fight. Mosul was turned into a giant arsenal, with weapons dumps and hideouts in every neighbourhood.
Before we climb back up the hill to the base, I look again on the dead fighters. In the grass beside one, I find a small piece of paper marked with an IS stamp. It is a leave permission slip. On the back, it is smeared with his blood.
The soldiers do one final check of the bodies. On the young man in the shadows, they find some cash - a small amount of Syrian pounds, almost worthless. But in his other pocket, there is something small and far more valuable - a memory card from a mobile phone.
The pictures on it will lead us to uncover fragments of the lives of the dead men, the deep camaraderie among them, their brutality, and their journey through the battle for Mosul. And it will cast light on the dead fighter in the shadows. Who was this young man and what secrets of Islamic State did he leave behind?
The photographs begin as bright family snapshots, but soon darken. The young man is seated, with the trace of a smile on his face. He is doe-eyed beside a little girl. Perhaps it is his sister. He holds her close, and she has her index finger raised - the Islamic sign for one true god.
His hair is curly, long and parted in the middle, and as the pictures progress they have been edited. His cheeks and lips turned a girlish pink, the whites of his eyes are touched-up and bright.
A transformation is taking place.
Soon he is in military gear, a Kalashnikov slung over his shoulder, a walkie-talkie in his top pocket.
In another photo, he is asleep. It is almost certainly posed, the intention is to show a warrior at rest.
This is no longer a family album, it鈥檚 now a record of a martyr-to-be, a baby-faced suicide attacker, cleansed and ready to sacrifice himself for his cause.
The memory card found on his body has other pictures, too.
There is a group shot of young men and boys. The fighter is not in the frame. Maybe he is behind the camera, taking the shot. I would later learn that most of the men and boys were from Mosul and were part of the Nineveh Fire Support Group, a rear-line, back-up unit. Their time in IS has forged a deep bond between them.
One of the most striking is a photograph of what appears to be the fighter鈥檚 brother-in-arms. This man looks older, his hair is long and is also parted. He stares intently at the camera. My eye is drawn to his hands, which are settled on his waist. Curiously, he is wearing black gloves. Underneath those hands, hidden by his shirt, there is a suicide belt. His thumbs rest on its bulge.
The gloves are worn to hide the switch that will detonate the explosives, disguised so that the target does not recognise the threat posed by the smiling young man in khaki, until it is too late.
There are group pictures, too, with older men. Battle-hardened and scarred, their faces are unforgettable. And to some in Mosul, they are familiar.
But the photographs from the phone card have another secret to reveal, one that was right under my nose the entire time.
The photographs begin as bright family snapshots but soon darken. The young man, is seated, with the trace of a smile on his face. He is doe-eyed beside a little girl. Perhaps it is his sister. He holds her close, and she has her index finger raised - the Islamic sign for one true god.
His hair is curly, long and parted in the middle, and as the pictures progress they have been edited, his cheeks and lips turned a girlish pink, the whites of his eyes touched-up and bright.
A transformation is taking place.
Soon he is in military gear, a Kalashnikov is slung over his shoulder, a walkie-talkie in his top pocket.
In another he is asleep, it is almost certainly posed, the intention is to show a warrior at rest.
This is no longer a family album, it鈥檚 now a record of a martyr-to-be, a baby-faced suicide attacker, cleansed and ready to sacrifice himself for his cause.
The memory card found on his body has other pictures, too.
There is a group shot of young men and boys. The fighter is not in the frame. He may be behind the camera, taking the shot. I would later learn that most of the men and boys were from Mosul and were part of the Nineveh Fire Support Group, a rear-line, back-up unit that sowed terror in the city. Their time in IS has forged a deep bond between them.
One of the most striking is a photograph of what appears to be the fighter's brother-in-arms. This man looks older, his hair is long and is also parted. He stares intently at the camera. My eye is drawn to his hands, which are settled on his waist. Curiously, he is wearing black gloves. Underneath those hands, hidden by his shirt, there is a suicide belt. His thumbs rest on its bulge.
The gloves are worn to hide the switch that will detonate the explosives, disguised so that the target does not recognise the threat posed by the smiling young man in khaki, until it is too late.
There are group pictures, too, with older men. Battle-hardened and scarred, their faces are unforgettable. And to some in Mosul, they are familiar.
But the photographs from the phone card have another secret to reveal, one that was right under my nose the entire time.
The men fighting in the battle for Mosul alternate between two states - the hyper vigilance of the battlefield and a swallowing exhaustion barely touched by a few hours sleep at night.
As a journalist following the men, I slip into the same routine. Rising before dawn, driving to the front, watching as they dodge mortar and rocket fire, avoid roadside bombs and drones. And ducking when IS snipers and fighters open fire.
At night there is barely time for my crew to edit, recharge our equipment, and get some sleep, before heading out again.
So we do not pay very close attention to our sleeping quarters. In short, it is dark, we are tired, and we have other priorities. All we know is they've been checked for booby traps and that we are relatively safe here.
After almost two weeks at the farmhouse, the bodies of the three fighters still lie where they fell. But the dogs and birds are at their corpses. They are increasingly unrecognisable.
As I go through the pictures from the mobile phone card again, the penny drops. These men did not just fight at the farmhouse. It was their home too. I recognise its walls and furnishings in some of the pictures.
Discovering the hideout:
On our last day at the front, with just a few hours to pack and return to the safety of Irbil, I decide to explore. Above my sleeping bag, there is a window. I remove the dusty curtain. Underneath are hidden notices from the caliphate, official IS orders.
They show IS struggling for resources, especially manpower and that the caliphate鈥檚 ranks are depleting fast.
On November 11, the Islamic State鈥檚 Minister for War calls for more special forces recruits.
By mid-December, new orders are issued to prevent desertion from the front.
At the back of a room, a blanket covers the wall. I can feel a draught from behind it, so I give it a sharp tug. In a cloud of dust, it falls away and reveals another room, small and bright, with a single window to a vegetable garden, and a bed.
This is the dead men鈥檚 sleeping quarters. Their clothes, and much more besides, lie scattered across the floor.
There is a Chelsea Football Club pillowcase lying beside IS wall posters, which list punishments for crimes in the caliphate.
Electrical parts are stripped from sockets and flashlights, presumably for military purposes. In the midst of the mess, something catches my eye. It is an anti-fungal medicine box with a blond-haired baby pictured on the front.
Its eyes are carefully gouged out. This defacement is likely because of an Islamic prohibition of the depiction of the human form.
The room is filthy. Hidden in the piles of material, something important has been left behind. A few pages of detailed handwritten notes and diagrams are carefully folded. They clearly meant a lot to the author, his IS staff number is written in the corner, and in bold English letters, his name: Abu Ali Al Moslaue. Is this the name of the young man depicted in the photos?
The handwriting is neat and careful in the beginning, and the notes are meticulous. They serve an important purpose, life and death, in fact. Abu Ali was learning how to fire mortars. It appears that he was an excellent and a diligent student. But like all schoolboys, he becomes more careless and erratic as the lessons drag on.
But he takes pride in his work. He notes practice runs in converting coordinates from Google Maps to actual targeting coordinates. He draws compass degrees as well as the curved graph course of mortar rounds.
Importantly, in the munitions section and in his own handwriting, he lists 鈥渃hemical munitions鈥 as a weapon.
There鈥檚 been much debate over whether IS has used chemical weapons in Mosul. Here at least, we know they are trained and prepared to use them.
He personalises his notes, sketching a logo for the unit and a makeshift IS stamp, labelled General Support Units.
And there are mottos: 鈥淚slamic State: Along the Prophet鈥檚 Methodology鈥 and 鈥淚slamic State remains, in spite of the haters鈥.
He used an Education Department exam paper as his notebook, and clearly finds this amusing.
He records the school year as 2016-17, Subject: Mortar, and scores his own paper: 鈥淔inal Marks: Congratulations. You passed. Total Marks: 100.鈥
The hideout has even more secrets to reveal. As I search through the detritus something catches my eye.
It looks irrelevant at first. The notebook is in tatters, hanging by a thread. Someone has scribbled the same Islamic poem and a prayer verse several times over a few pages, as if to etch them into memory. There are mistakes, the handwriting is shabby, the structure unappealing. This definitely doesn't belong to Abu Ali.
But then numbers emerge, names, tables, tabulations and permutations. Whoever scribbled those names and numbers had the authority to dispatch patrols, put men on shifts together, see how many rounds they fired and how many they need for their next outing.
It definitely belongs to someone senior at that farmhouse, possibly the commander of those men. I discover his name is Abu Hashem.
The notebook reveals its secrets - it is a unit鈥檚 logbook from the Al-Buseif Air Defence Brigade, a sub-unit of the Nineveh Fire Support Group. They must have all been sharing the same farmhouse.
All in all, Abu Hashem commanded eight men and two vehicles. They formed the bulk of the Al-Buseif Air Defence mobile patrol. They drove a Hyundai pickup truck with a double-barrel anti-air cannon, and another pickup truck with a smaller calibre, single barrel heavy machine gun. Both vehicles were white, which is reportedly the preferred colour for Islamic State combat vehicles because they鈥檙e easier to camouflage with dirt and blend into the terrain.
Commander Abu Hashem appears to have been diligent. He meticulously records the sorties, the types of weapons used, the chassis number of his trucks, how many rounds they had, their type, how many rounds fired - even the faulty ones.
Not only was he a good logistician, but he also understood how small units worked. The record shows how he tried to foster and strengthen bonds between his men. Scheduling their lives, Abu Hashem made sure to couple fighters serving on the same vehicle to have meals together.
And so, while he鈥檚 having lunch with Abu Riad, his driver, Abu Hafs, the driver of the other vehicle is paired with a gunner, Abu Al-Sham.
The commander, his logbook shows, has clearly put some thought into this. He worked on two possible permutations, crossing off names before putting in a clean draft.
The burden of command must have weighed heavily on Abu Hashem鈥檚 mind while commanding his troops. This, however, didn鈥檛 soften him up.
Like any seasoned commander, he proved ready to show a tough disciplinary side. In one written order, he tasks one of his subordinates to lead a patrol. 鈥淭hose who are found lacking must be punished,鈥 he orders. 鈥淢ay Allah reward you with goodness,鈥 wishing him well.
Taking the photos and the bundles of documents with me, I leave the farmhouse and finally Iraq. But for months, the men remain in my head.
Using what I already know about them, would I be able to find out more? Did they have families? What kind of lives had they led?
My search to find out more about the men begins in Mosul. It is early April and the 1st Brigade of Iraq鈥檚 ERD forces are deep inside the west of the city.
The farmhouse seems like a lifetime ago. Their new base, a house near the front lines is in a residential neighbourhood.
The steady thump of mortar fire rattles what is left of the windows. Captured IS suspects are being brought here. One man is pulled from a pick-up truck by the fighters.
He has been badly beaten. His T-shirt is covered in blood. It is not clear who hurt him.
It may have been the troops, or it could have been locals exacting revenge on those who had controlled and oppressed them in the preceding years.
An intelligence major calls me into a back room. 鈥淚 have someone for you to meet, someone we haven鈥檛 shared with anyone else,鈥 he says.
A young, shifty-looking man, slight and dressed like an off-duty soldier comes into the room. Let's call him Ibrahim.
He fought with IS for two years, but he is not a prisoner. He is a double agent, working for the Iraqi security forces.
I show him the photos that I have brought from the farmhouse.
Quentin speaks to Ibrahim:
鈥淚 know them very well,鈥 he says. 鈥淭hose are fighters. They were with the Khaled Ibn Al-Walid Unit. This one was the section's commander,鈥 he says pointing to one of the older men in the photographs.
鈥淭hey acted as a support unit for the front-line troops. They would spring into action as soon as they were needed.鈥
Along with the intelligence major, he confirms the men were mostly from Mosul. Ibrahim reflects on what his membership of IS had done to him, and most likely to the men and boys in the pictures.
He notes that men from the Nineveh Fire Support Group lived spartan lives. 鈥淵ou should live like the Prophet, a simple life. A fighter needs very little to survive,鈥 he says.
It is clear from Ibrahim and others that I meet that most of the men and boys in the pictures are dead.
Identifying all the men in the photographs has proved impossible. IS fighters use noms de guerre, but there was another factor at play.
As one member of the Mosul's special forces team explains, "When IS came they were children, we don't recognise them as men."
Long before their advance stalled around Mosul鈥檚 old city, Iraqi forces advanced far quicker than expected towards the city鈥檚 western side. And it appears it was much faster than the Nineveh Fire Support Group anticipated.
Abu Ali and his brothers in arms had no time to destroy the material in their hideout. Their grasp of operational security was weak.
A slip of paper discovered on the floor of the farmhouse turns out to be coordinates of locations across Mosul.
Using Google Earth maps, I plot the information. I recognise one location - an IS mortar factory that I had visited in November 2016. The other coordinates are mortar storage and production units too, according to Iraq security forces.
About a dozen men had worked at the factory producing precisely milled mortar shells.
They had burned oil fires through holes in the building roof to hide it from coalition aircraft.
By the time we return to the mortar foundry in April, it is cleared of the shells and returned to commercial use.
Now it is making water tanks and roofing to replace those damaged in the fighting.
In November, people were willing to talk about the IS fighters who made weapons there, but by April, a wariness has settled on east Mosul. Locals may be freed from IS, but it feels like the militants are not very far away. The fear of retribution hangs in the air.
And it becomes easy to understand why when I make my way to the final destination in the journey to retrace the men of the Nineveh Fire Support Group.
In amongst the papers and documents I retrieved from the farmhouse are a number of religious books.
All are marked with the stamp of a mosque in east Mosul - one bearing the name of an imam has been dedicated to the young men.
The Al Mou鈥檓eneen Mosque is not far from the mortar factory, and it is here that the group from the farmhouse prayed and brought terror to the local neighbourhood.
The mosque is modest and mostly without adornment. It is a bright spring day, and children are making their way home from school. But I have a sense of trepidation as I knock on the metal door. Is the imam who dedicated the book to the fighters still inside?
The caretaker answers and welcomes me inside. I take off my shoes and he sends a boy to find the imam. I sit waiting in the sunshine, drinking some sweet tea, listening to the children playing outside.
The imam who signed the book is long gone, he fled with IS. So the caretaker calls to find the man who led prayers before IS took control of Mosul.
The imam arrives, his name is Fares Fadel Ibrahim. He is younger than I expected, broad-shouldered and with a quiet confidence.
I show him the pictures of the fighters and he recognises most of them.
Quentin speaks to the imam:
He is nervous, though, and I soon discover why. 鈥淧lease,鈥 he asks, 鈥淒o not film me looking at the pictures.鈥 Why is he afraid of these young men?
The fighters, he says, moved their entire families into this neighbourhood. Most were Iraqi, but there were foreigners, from Syria, Morocco and elsewhere, he says. They lived among them for more than a year and fled in November 2016 when Iraqi security forces advanced closer to the area.
Mullah Fares is, he explains, the temporary imam until the Department of Religious Affairs appoints someone permanently.
That said, it is clear that this is his mosque. He has prayed here since he was a boy - since the mosque was built in 1980. And then he preached there alongside the permanent imam, until IS came.
鈥淲hat happened to the permanent imam,鈥 I ask. 鈥淭hey murdered him,鈥 he replies. And replaced him with their own preacher - the man who dedicated the book to the fighters. He called them "beloved darlings".
As we sit on the carpet together in the prayer hall, he explains the story of IS in Mosul and his neighbourhood. They corrupted the city, he says, and worse still, the world鈥檚 view of Islam.
At first they treated people well, he explains. 鈥淭hey came with respect and appreciation and then their true intentions appeared.鈥
For IS, the mosques are a means of control and of recruitment.
Mullah Fares was given the option - join IS or stay at home and only return to the mosque he loved, to pray. So, he returned home.
IS set about a purge. Other preachers were accused of being 鈥渄elaying salafies,鈥 and were imprisoned for a month, or longer. When released they promised never to lead prayer again. Others, like the Al Mou鈥檓eneen鈥檚 permanent imam, were killed.
Looking at the pictures of the young men from the Nineveh Fire Support Group, Mullah Fares pauses for a moment, then says: 鈥淭he power is with the person who holds the gun, even if he is very small and young. Like the young men from ISIS [IS] who killed some strong and old men of ours, like the imam here in the mosque, who was killed by children.鈥
It would soon be time for afternoon prayers and we have to finish the interview. Dozens of curious children are crowded around the mosque鈥檚 door, eager to get inside. But before Mullah Fares finishes, he has one more thing to say, about the young men who held this city.
He continues, 鈥淢y dear brother, we are by nature people who love faith, young or old, we love Islam and Muslims. Even the prophet, while he encouraged invading different places, he ordered his men not to kill a child, a woman, or an old man, and not to cut down one tree. So where were these values of Islam?鈥
And with that, he stands up and begins the call to prayer. From the sunshine outside, the waiting children burst through the doors and get ready for their lessons.
The three dead fighters on the banks of the Tigris were little more than children. In fact, one was still a child. The Nineveh Fire Support Group were enthusiastic in their campaign of destruction and terror. They helped turn parts of their city into a ruin, and furthered the corruption of their faith.
Did they die happy, knowing they had served their cause as was asked of them, I wonder.
They died as fighters, but they died as fools. Pity should be reserved for the people they once lived among, who were abused and killed as the young men sacrificed all around them, for their caliphate.
When they left Mullah Fares鈥 neighbourhood, they said to the people, 鈥淵ou did not take care of the caliphate, so you do not deserve it.鈥
But the truth of their cause was revealed when IS went into homes and destroyed them, killing families. IS and the Nineveh Fire Support Group had no love for Mosul nor its people. The young fighters were willing recruits, but they were also manipulated.
Quentin studies the photos:
As I retrace their steps through Mosul, the thing that strikes me most of all is their youth. It surprised almost everyone we spoke to. For IS, a fighter is anyone above the age of 15, but some of their recruits are much younger.
IS has had support in Mosul, but it inflated that support by weaponising children. Taking the young and the gullible and sacrificing them for its malicious cause.
In Mosul, IS is on the brink of defeat. The bodies by the riverbank are gone - carried away by dogs and other animals.
There is no longer any trace there of the young men. But their legacy of turmoil and destruction remains. It stretches far beyond Mosul, and far beyond the flow of the River Tigris.