The heady mix of sweat and testosterone fills the weights room at Mountjoy Prison and it seems as though all of Dublin's toughest criminals are crammed into this tiny gym.
ulging muscles protrude from perspiration-soaked tank tops, tattooed arms pump iron and the roars from inmates make it almost impossible to hear. One man proudly displays his biceps by holding them out in front of his chest as he walks. Fists squeezed tight, in a dramatic clenching gesture. For a moment I laugh, thinking he is doing this ironically. But no, these are some of Ireland's most violent criminals - peacocking.
Governor Eddie Mullins tries to narrate over the bellows and whistles. I nod and smile ,but I can't hear a word he is saying. "Can I talk to them?" I shout, and he laughs as though I have made a joke I'm not in on. "No," he is bemused, "not these guys."
Outside we look through wire mesh and on to the exercise yard below.
I say ''exercise yard'' but it is a small rectangular cage where prisoners walk around and around in circles. They move in huddles of twos and threes, deep in conversation, occasionally breaking away to look up over their shoulder at the governor. "The sad reality is a lot of these are probably planning their next drug deal," he says, before moving us inside.
Mullins (53) is a warm, affable character, with a relaxed humour that is completely at odds with his surrounds. A trained chef, he worked in The Westbury Hotel before deciding to try his hand in the prison service. In his early days, while still "a red raw recruit", he found himself smack in the middle of the notorious prison riots of 1991, when more than 50 criminals charged at officers, attacking them with pool cues and smashing a snooker ball into the head of a staff member.
Mullins left his shift that night "sick to the stomach" at the ferocity and suddenness of the chaos. He spent a week regaining his nerves by helping in the prison kitchen.
Twenty-nine years later, and no longer so green, he oversees Ireland's most dangerous inmates. Mountjoy is home to many associates in the Kinahan cartel, as well as convicted murderers and guns-for-hire. He has a physically commanding presence and gets nods of respect as he walks through the prison.
Inside the jail, he takes me to ''the circle'' with its large metal bell - ''the auld triangle'' made famous by Brendan Behan and then The Dubliners - a nod to the days it was used in the mornings to rouse inmates.
But that's where the romanticism stops.
Here, two prisoner-on-prisoner attacks happen every week, according to latest figures, with staff often direct targets. They have been slashed with blades and doused in boiling water. Some have had their bones broken. In one incident, a prisoner held a syringe filled with his hepatitis-infected blood to officers' necks, with the intention of forcing them to drink it.
"Every day you will see the full spectrum of human emotion. It comes at you hot and fast," says Mullins. "It's high-octane stuff."
It is a "brutal" and "a nasty, nasty place", according to another member of staff who works at helping inmates get an education.
She has her work cut out.
One in two prisoners has left school before 15. In 2008, of the 520 prisoners who enrolled in school here, 20pc could not read or write and 30pc could only sign their name.
When discussing money-saving techniques one day in class, a teacher recalls how a man looked at her incredulously: "I can only tell the cereal is cornflakes by the image on the box," he said. Reading the price labels was beyond him. Others have spoken about their frustration at trying to fill out forms in their local dole office. The angry queue forming behind them as they grow hot with shame unable to read the page. A row inevitably erupts.
The main jail is made up of four long wings radiating from a centre circle with its distinctive spiral staircase. Each wing is caged off [a lesson from the riots] and divided into three landings above and below.
Of more than 700 inmates, there are now so many prisoners from different gang factions that each cell door has to have a special coloured card to differentiate the men who need to be kept apart at all times. One wrong move could mean the difference between life and death.
Mullins is resolute that, under his watch, gangs don't have control. "Absolutely not. Gangs have been a phenomenon in prison for many, many years - the focus now is on two [main] names but there is nothing new in it."
But surely the level of violence is more vicious? "Social media has added to this platform and everything is reported in real time so it creates a frenzy around gangland culture, but it has always been there. In terms of the calibre of prisoner, I haven't seen a dramatic change."
In Mullins's eyes, ruthless criminals have always existed. He has housed psychopaths, some still in the system: "They are cold and callous and have the propensity for instant violence," he says, snapping his fingers. But what surprises him most these days is the baby faces that match the crimes.
"You have an expectation of the Al Capone type coming in and they are not that. They are often very young, vulnerable men who have been sucked in and they aren't afraid to use a gun. But they aren't as dramatic as your expectation. You think 'My God! This guy is charged with that?' The reality is some of the most vulnerable people are dragged into crime and some will commit the most heinous crimes."
Back in the jail, the smell of the prisoners' food wafts down the corridor, flipping my stomach. The governor brings me downstairs to one of the base wings and it's time for another deep breath. He sniffs the air as we make our way through a tight corridor."Get that?" he asks, "Weed… somebody is having a party."
Staff do their utmost to stop the tide - but drugs still flood in. The innovation knows no bounds. Everything from ecstasy to heroin has been dropped by hi-tech drones, stuffed inside chocolate eggs, and often passed over through intimate moments with girlfriends and wives.
On the outside, those relationships can cause havoc. Mullins describes how each man gets a six-minute call [the number depends on his sentence and behaviour]. Often communal phones are broken from the wall.
"There can be relationship troubles, things can get heated and then someone loses their temper," he explains. Jealousy and paranoia seep into conversations and the prisoner can do nothing but storm off to brood in his cell.
In the bowels of the prison, protected prisoners are housed in special observation units for up to 22 hours a day. This can range from a few days to several months at a time.
Although the term is used worldwide, the word "solitary confinement" is not used for the cells here. Mullins says it is "a punitive term" that "suggests we are punishing people".
"It's the opposite," he explains. Many request sanctuary here for their own protection. At times it's from other inmates, but often, from their own minds. With 70pc suffering from addiction and a high number battling ''severe mental illness'', the impulse towards suicide is high.
We walk down the corridor to the sound of Ed Sheeran's You Need Me, I Don't Need You coming faintly from behind one of the heavy steel doors. An open neighbouring cell is lit up with a garish neon blue light. The special hue allows staff to check the prisoner every 15 minutes through a steel flap in the door without waking him from his sleep.
So where is the way out?
First through getting clean, Mullins says. Above all, the inmates have to show "willingness" that they want to stop if they have a drug addiction. In this respect, initially at least, he has no trouble finding surrendered souls. In the privacy of one-to-one interviews on arrival, many beg for help. Through the Mountjoy services, countless find recovery.
He seems visibly moved when he speaks about the prisoner with a severe drug habit who kicked the scourge and got his life back on the inside. Recently he helped the governor over the finish line on one of the prison's weekly park runs. Another former addict now teaches yoga to fellow inmates who are following him down the same path.
Education is the second key to breaking the cycle. Many prisoners have passed their State exams, some with honours, and have gone on to complete degrees. Staff can sometimes hear inmates call their children who are sitting the Leaving Cert at the same time. The parents and children wax lyrical about Irish and European history and other subjects. The message down the phone line is that if they can do it, their kids can, too.
If he had the power to change one thing, Mullins says it would be to ask "big business" to exercise its social conscience and give reformed prisoners a chance. He cites the UK shoe repair company Timpson, whose managing director James Timpson famously funds a training programme for ex-offenders. Timpson says they are among his most trustworthy and loyal members of staff. "They have more to lose, have a strong desire to show their families and the world they can succeed and want to repay the trust we place in them," he has said of the initiative.
Mullins believes Ireland needs just a small handful of brave companies who are willing to follow suit and help those who want to change.
"When they [prisoners] leave here, one of the biggest challenges outside is boredom. There is nothing to do or occupy their mind." It is a myth, he says, that prison causes people to relapse.
"The reality is recidivism isn't caused in prison, it is caused in the community. When a person goes out, if the supports around addiction, homelessness and employment are not there, they drift back into crime and back into prison."
Big business could lead the way, he says, step up and show "social conscience" in the community. Otherwise there are too many forces, stretching their tentacles out, hoping to suck them back in.