“There’s this irreducible responsibility of the author to put the words down and stand by them. You’re in this position of being a thoughtful filter between the source and what gets presented, and trying to do right for them and the reader. It’s complicated, and I don’t want to be glib. These are real people’s lives, and they go on outside of the book.”

It’s been two weeks since punters were turned away at the door of St Andrew’s on the Terrace church in Wellington, where defence lawyers, prosecutors, judges and counsellors joined the literary set for the packed-out launch of The Valley. A fortnight beforehand, he’d appeared on stage at the Auckland Writers Festival alongside literary non-fiction heavy-hitters Patrick Radden Keefe and Barbara Demick, and had The Valley named Book of the Year by Newsroom. Better than all that, people are reading the book: it’s a nationwide best-seller, has 152 holds at the Lower Hutt library, and my kid’s friend’s mum asked me courtside at Miniball if I’d read it (a true sign of a breakout hit).

It’s enough to turn this previously low-profile lawyer and journalist into a reluctant main character. If everyone wants a piece of him, it’s because, somehow, Emanuel has done the impossible: he’s taken the mundanity, the dark humour, the Groundhog Day-ness, and the heartbreaking hope that’s at the heart of the everyday grind of the district courtroom and held it to the light in a way that makes you actually look at it.

New Zealand Geographic’s Naomi Arnold called it a “remarkable” book. “Emanuel’s broader work … is in showing his readers that the main drivers of crime are not individuals themselves but poverty, housing instability, lack of education, addiction and racism.”

Conceived eight years ago out of frustration with what he witnessed in court as a junior barrister, and how the justice system was presented to the public, the book follows two Lower Hutt men, Nathan and Rikihana, and their tireless public defence lawyer Lewis – all the names in the book have been changed – over 18 months. Their stories cycle through courtrooms, rehab, probation, welfare and drug counselling appointments, boarding houses and the street to show how a system focused on punishment – in a country where rates of imprisonment have rocketed since the 1980s, to twice that of Canada – ultimately fails them. The two men are jailed and trespassed, bailed and remanded in a kind of Kafkaesque nightmare for crimes that range from stealing $8 of baked goods from Countdown to lodging an axe in a car windscreen during a bender, in lives fuelled by drugs, alcohol and trauma.

Although the courtroom is the apparatus of the state, most New Zealanders won’t have seen the inside of one; the latest Crime and Victims Survey, Emanuel says as we walk past the Countdown where Rikihana was trespassed, shows most people’s involvement with the system stops at a roadside breath test. The public learns about what’s happening through crime reporting, which often highlights the juicy or most shocking elements.

“In a way, I was writing against that,” Emanuel says. “The reality as shown by the news media is systemically inaccurate; the criminal justice system doesn’t stop. It’s so tied up with what happens at Winz [Work and Income], what happens with housing.”

And so, every day for more than a year, Emanuel became so well known to security staff at Hutt Valley District Court that they waved him through screening. He stood when the judge entered the courtroom, and he listened. Eventually, the book coalesced around three main characters who allowed him to tell the story of the system in what he felt was the most representative way, even as this railed against conventional modes of storytelling.

“I was cautious about being misled by ‘narrative’ or by all of these different frames that can in some ways get us further away from the truth. This whole ‘If it bleeds, it leads’; this desire to impose the hero’s journey or the recovery narrative onto what we’re observing and tell that story.

“There are no big flashpoint incidents in the book, and that reflected the experience of researching it. Instead, there’s the repetition, the grind, the churn of the process. For these guys, the normalcy is being in the criminal justice system.

“And it turns out, that’s quite sad.”

Emanuel was raised in Westmere, Auckland, by a mother who was a psychiatric nurse, and a father who was a gardener and handyman. He went to Saint Kentigern College, a prestigious private school, on a scholarship, and says he was aware of class differences growing up.

“As a child going around town with [mum] in Auckland in the 90s, we would see men on the street who knew her, because they’d been patients in hospitals where she had been a nurse, prior to the deinstitutionalisation of the 80s and 90s, which saw many people moved from a medical setting to either a correctional setting or homeless.”

He admired his mother’s compassion and the “equanimity” that she managed to hold in the face of people’s crises.

His thinking about inequality shaped the way he approached The Valley. “If you have a big mental health crisis, you start suffering from addiction, you commit a crime, you lose your house; if you’re part of a family and a group of friends who have stability and resources, there are ways that people are able to be helped back up. With Nathan and Rikihana, these things are not there, and stuff spirals because of that.”

He studied law and English literature at Victoria University of Wellington, and in his third year co-edited the student magazine, Salient. He snagged a judge’s clerk position at Wellington’s High Court, while starting the Policy.nz online election guide with friends ahead of the 2017 election, then worked as a barrister while writing stories about politics and justice for The Spinoff. That’s when he conceptualised The Valley.

“I felt there was a gap between what the public had through the news media and what people who went through the system or who worked in the system knew. And that gap, this was my story. How was I going to tell that?”

After doing a “gruesome” amount of reporting, with the help of a grant and relatively frugal living, he sat on the notes for a year, daunted. In his tidy office in Masons Lanes Chambers in central Wellington, where he practices civil legal aid law, Emanuel shows me his neat indexed notebooks, the bound books of interview transcripts. He realised – to the surprise of his publisher BWB books, which expected a straightforward academic tome – that he had enough material to write it as narrative non-fiction, in a novelistic style. This also meant he could remove himself from the story as much as possible, he says.

“It was really important to me that the reader would be able to have their own experience of meeting these people and seeing what was happening and reaching some of their own conclusions.”

Is this why he’s been so uncomfortable every time I ask him a question about himself? “Yeah. I don’t like answering personal questions, and I’m not in the narrative of the book. I’m trying to fade into the background, because it’s not about me.”

But the task was mammoth, and at times he felt he was drowning. “My partner reminded me the other day of a point at which I’d suggested that I felt like I might be too depressed to finish the book. I asked her, ‘Would everyone be okay if I didn’t finish?’

“I really lost faith in the possibility of writing or journalism to influence the world. I think that was partly a result of the field work and just coming into contact with the sheer weight of the historical forces that are shaping the criminal justice system, New Zealand society, and feeling a real sense of total powerlessness.”

Friend and former Salient co-editor Oliver Neas says it was clear the book took its toll. “You got the sense the Asher at the end was different to the one who started it.

“It’s a testament to him, keeping the faith to the project and persevering. He’s very organised, he’s very driven, he has an unusually clear sense of justice, and this book was only possible because of the sense of trust he inspires in people.”

Whether he wants it or not, at some point, Emanuel is in this story. It did impact him; his characters are people, and they’re often struggling. Sometimes they want things from him. Rikihana asks at one point if he can get his dole paid into Emanuel’s bank account after a Work and Income meeting. “And I’m running through my head, like, what are the consequences of saying yes here? Like, probably the point at which I’m receiving his money will bring this to an end as a source/reporter relationship.

“I was thinking about trying to explain myself to him why I can’t. And I was like, this is not morally going to make sense to him.”

Another solution was found, so Emanuel was off the hook, but there are other times when he does intervene – a departure from traditional standards of journalistic neutrality – such as when Rikihana is released from prison, penniless and hungry, and Emanuel buys him some food.

“I suppose I found myself faced with the choice as to who was I going to put first? And I guess I found out what the answer was.”

In the lengthy endnotes, Emanuel has disclosed and described these moments, along with meticulous references. With the help of his editor, Anna Hodge, 70,000 words were shaved off the original 220,000-word manuscript. He shared the final draft with those in it, which included visiting Nathan at his mum’s house to read it out loud.

The response to publication is heartening; it’s taken a long time, a lot of his life, and he’s glad people are reading it.

Near the end of the book, Rikihana and Nathan meet; one on their way into Rimutaka Prison, one back out.

As the gears in the system keep on grinding, then, is Emanuel hopeful?

“I’m neither hopeful nor despairing, but I do feel more clear-eyed about what the problem is, and I hope readers will find the book clarifying, too.”

Into the Valley: Crime and Punishment in a New Zealand City, Bridget Williams Books, $39.99.