BBC Three takes an unflinching look into Hydebank, the young offenders' institution in Northern Ireland - revealing the sometimes harrowing personal stories of the inmates, what life is like in custody and how they are challenging the choices that led them there.
The scars up the arms of young offenders tell part of their story.
"I used to get so stressed out, go into myself, and rip my arms to shreds," William says. "Because of what I'd done… Like I've been on the phone to my family, crying, crying and crying my eyes out and I'll go, 'I can't deal with what I've done here.'
"It doesn't help, doing that there."
William entered Hydebank Wood Prison in Belfast on his 18th birthday.
"I was in the court cells and I thought I was going to get bail again and then [the judge] says, no. So I was sitting in the court cell and they came in and they hand you this wee leaflet for Hydebank, and as soon as I walked into this place everybody knew who I was. I was immediately told I was under threat."
He was convicted for a vicious high-profile attack on a 16-year-old girl - a video of the attack went viral, in which he can be seen pouring alcohol onto her face as she was violently beaten by two others. He was ordered to spend half of his 32-month sentence in custody and half on licence, after pleading guilty to causing actual bodily harm.
Speaking after the sentencing, a detective constable said in a statement: "This was clearly a traumatic ordeal for the victim."
Hydebank houses around 100 young offenders and also suspects including those on remand. Most of the convicted inmates are aged between 18 to 21 and have committed offences ranging from theft to murder.
In William's first week in custody he was attacked and had his bed urinated on. "I opened my door, went out to get a mop bucket, came back down and got hammered."
"That mistake's going to haunt me for the rest of my life... I hated what I've done, I regret what I've done. And if I could go back I would have changed it, and she wouldn't have got touched."
Throughout the documentary, inmates from Hydebank share details about their difficult upbringings, including what it was like growing up in a care home and the effects of experiencing sexual abuse at a young age.
Young offenders are high risk for suicide and self-harming behaviours and many enter the system with existing mental health conditions and drink and drug addictions.
Some of the men who spoke to the BBC almost casually opened up about attempting suicide while at Hydebank.
One anonymously shared, "I tried it once when I came here and I got put in the observation room." Another added, "Once you come in here, coming down off drugs and all, and once the door closes your head does go a bit."
The Ministry of Justice says self-harm in prisons and young offenders' institutions is at a record high in the UK.
In 2019, there were 63,328 reported incidents of self-harm in custody - the highest ever recorded figure and a 14% increase in compared with the previous 12 months, in England and Wales. The figures published in the Ministry of Justice's Safety in Custody Statistics, showed a 110% increase in incidents involving 15-18 year-olds in custody.
Dr Richard Kirk, Clinical Director at Hydebank, says he sees many cases of self-harm: "It can be quite dramatic. Prisoners with lots of scars along their arms. That's the classic version of a young person who has got some mental health problems and self-harming.
"People often use it as a way of release, to help them deal with things, or as a demonstration of what's going on behind the scenes."
Andy Bell, Deputy Chief Executive for the Centre of Mental Health, says: "Children in the youth justice system have very high levels of poor mental health and are a very vulnerable group of young people. Those who are placed in custody are even more vulnerable. Many will have been through numerous traumas in their lives, and being locked up will make the effects of those even worse.
"Those who are in custody need to be made to feel safe, in an environment where wellbeing is a priority and help is available whenever it's needed."
Following damming reports, Hydebank was completely overhauled as a prison in 2015 and rebranded as a "secure training college". Free movement, education and training were introduced alongside a change in culture. Labels like "prisoners" and "inmates" were replaced with "students" – with both students and staff being called by their first names.
But from 7pm to 8am residents are locked in their cells.
Hydebank Governor Gary Milling told the BBC: "People are challenged to look at their offending behaviour, what are the things that led them to be here?
"This isn't 'Easy Street' by any stretch of the imagination. This is actively asking people the question, 'Why have you come here? What is it you have done that has damaged lives of other people outside? And what are you going to do about it, about changing that in the future?'"
If you’ve been affected by the issues raised, advice can be found here.