It's easy to see why Harper Collins and the Ngaio Marsh estate approached Stella Duffy to complete Marsh's unfinished 1940s manuscript Money in the Morgue.
Like Dame Ngaio, our most celebrated crime writer, Duffy's a writer (17 novels and counting), theatre lover, knows London and New Zealand (she spent her formative years in Tokoroa before returning to London in her 20s), loves genre fiction - her latest is the excellent The Hidden Room - and is a passionate promoter of the arts.
Still the email that arrived in her inbox in 2016 gave Duffy pause.
"I was honoured, don't get me wrong - but hesitant too because I'd never done anything like this before. The request came as a complete surprise as I'd had no connection either to the estate or Harper Collins."
And it wasn't an easy job; the manuscript Duffy was given had just three chapters and a few notes - and nothing about who had committed the crime or why.
"Her first three chapters are pretty much as you read them in the book," says Duffy, "with a few additions from me to make sense of the plot later. Chapter four is half her, half me and the rest is all me."
The result is an engaging "cosy" that should bring our Queen of Crime to a new generation of readers - with Scottish crime star Val McDermid hailing it ". . . a remarkable act of ventriloquism . . . I defy readers to see the join."
Duffy says there are various theories around why Marsh abandoned the book, written while she worked as an ambulance driver in Christchurch during World War II.
"One is that some of the story echoes a romance she may have had during the war that she didn't want to write about; the other is that she just got sick of writing about the war. Marsh loved London and wanted to return and quite possibly didn't want to continue with a novel set in New Zealand."
Although Golden Age detective fiction has enjoyed a resurgence of late - with Sophie Hannah continuing Agatha Christie's Poirot series with some success - Marsh's reputation has languished since her death in 1982.
Indeed, her name may be best known here through the annual Ngaio Marsh Awards that celebrate the best in local crime writing both fiction and non-fiction.
"Marsh is not like Christie in that she didn't have children to push her work once she died," says Duffy. "Christie's estate is very much pushed by her grandson in Britain. That's why her books have remained in the public eye.
"But you have to remember when they were contemporaries, for a good chunk of that time, Marsh was more successful than Christie, but these days she's much less known but hopefully Money in the Morgue will help change that."
Duffy knew Marsh's work but more as a theatre person than a novelist.
"I'd read some of her books when I was a teen in the 70s when I was frankly desperate for work by any Kiwi women because there were so few being promoted," she says. "I think New Zealand has always been rather snobby around genre fiction.
"Things are a lot better now - and the work Craig Sisterson has done around the Ngaio Marsh awards is fantastic - but when I was growing up, the bookshops had a fiction section and a literature section as if they were separate things. So, of course, I read her but back then I did have some of that snobbishness myself."
Before starting the project, Duffy went and re-read the Alleyn novels, wrote a 12-page proposal and submitted it to the estate for approval, something she had never done before.
"And that was strange for me but I did it because there are other people concerned; it's not just me writing what I want. Of course, the estate wants people who haven't read her work to go back and read it, so it was important I keep to her style."
Her favourite of Marsh's novels is still 1945's Died in the Wool - "a fantastic book" about the murder of a New Zealand parliamentarian on a remote Canterbury sheep farm - although she is less enamoured of Marsh's novels set in London.
While Duffy keeps the 1940s' prose style - lots of adverbs and conjunctions - she also felt it was important to make Money in the Morgue relevant to modern readers so there's a character with PTSD post-war and emotions we would experience now. Duffy also introduced a Maori soldier, a character not in the original notes.
"I didn't want to write a novel set in New Zealand and not have a Maori character in it. I think, for her time, Marsh wrote pretty good Maori characters, not the best or most inclusive, but pretty good, but she also did have a touch of the 'noble savage'. I hope I haven't done that and have written a character more true-to-life of the time."
But Duffy admires how Marsh brought a degree of realism into "the cosy". What's a cosy? It's a sub-genre of crime fiction in which sex and violence are downplayed and the crime and detection take place in a small, socially intimate community. Cosies are in contrast to hardboiled fiction, which feature violence and sexuality more explicitly and centrally to the plot.
Any way you look at it, it's a formulaic genre.
"The usual set up is you have a crime, a bunch of suspects and by the end you find out whodunnit because you have a detective who's cleverer than the rest of us," Duffy says.
She was also conscious that her late father, who served in the air force during World War II, spending four years as a POW, would have been the same age as the quarantined soldiers in the book (they are waiting for the medical all-clear before they return to the war).
"These men had hard wars, it wasn't this glory thing. Many New Zealanders lost their lives or came home damaged and that's not known so well over here, and it was important to me to acknowledge that."
Still, a lot of research was required especially around colloquial sayings and the speech patterns of the New Zealand characters at the time.
"The problem is I think I remember my father's voice and his turn of phrase, but I wasn't sure. So I looked at Frank Sargeson's short stories and Gordon Slatters' A Gun In My Hand - which is such an under-rated book, really brilliant - and both were helpful."
Less troublesome was Marsh's signature character gentleman detective Roderick Alleyn. Duffy describes him as a "really juicy interesting character" to write; literally a gentleman, an aristocratic but also, despite his awareness of his social status, self-deprecating. She especially liked that he doesn't think he's cleverer than everyone else in the room.
"Oh, I think Marsh thinks he is, but Alleyn doesn't. That means that a degree of police procedural comes into the work, a degree of puzzle.
"But I was always aware that Alleyn fans really love him. And inevitably there'll be people who think I haven't captured Alleyn's exact tone when he's talking to a subordinate or haven't got this or that detail right and that's okay; that's why it says by Ngaio Marsh and Stella Duffy on the spine. Hopefully a modern audience will go back to the original books and see how I've done and who this character is."
Although Duffy enjoyed the process of completing a cosy, her natural inclination is for the gritty modern crime novel. She has strong views on the reasons behind women's embrace of the modern crime novel, both as readers and writers. "Our world is still led, pretty much, by men. Generally speaking, even women who wouldn't call themselves feminists feel scared walking down the street on a dark night, still feel uncertain being in a waiting room with a strange man. And in the crime novel we can reveal or indulge those fears.
"These are things that women deal with on a daily basis. That's why I love the modern stuff, because we're not trying to tie it up neatly at the end. It says life is unfair, bad things happen to good people and good people do bad things.
"It also goes back to literary snobbery. Ask any publisher and they'll tell you women buy more books than men, and if fewer men are going to buy novels and if publishing is still snobbish around genre then men are less likely to buy genre books.
"It really annoys me when I hear people say, 'oh, I don't read crime' and I think, 'so, you don't like Shakespeare? And you don't think Dostoyevsky is a good writer?' Because Shakespeare's full of crime and what is Crime and Punishment if not a crime novel?"
Who was Ngaio Marsh?
Born in Christchurch in 1895, Marsh was considered one of the four original Queens of Crime along with Dorothy L. Sayers, Margery Allingham and Agatha Christie. She's best known for her 32 detective novels featuring detective Roderick Alleyn; was awarded an OBE in 1948 and became a Dame (DBE) in 1966 for services to New Zealand theatre. She died in 1982.
MONEY IN THE MORGUE: THE NEW INSPECTOR ALLEYN MYSTERY
by Ngaio Marsh and Stella Duffy
(Harper Collins, $30)