Girl in the Mirror was life-changing for author Rose Carlyle. Her second book makes her feel it wasn't a "fluke".
That second book is No One Will Know, a "twisty, plot-driven" novel, she told RNZ's Nine to Noon.
It's about a wealthy couple who take in heroine Eve and her baby, raising the baby as their own while she's retained as nanny.
The thriller delves into illegal adoption and the dubious actions of the wealthy.
It was, she said, a "great feeling" to publish her second novel.
"Because you do feel like you fluked it the first time. And I think everyone struggles with the second novel, just as musicians struggle with the second album.
"I really wanted to take the time to get this one right, and it also feels so great, the new thing about having a second novel is that I've got fans out there already waiting for me. "
The new novel came about when she first imagined a twist in the tale, she said.
"I kept thinking, this would be such a great twist I've never seen it written before. I don't think anyone would guess it.
"And I didn't have a story for it to happen to. So, it took me a long time to get from there, because the twist happens in the middle to end of the book, to get from there to a full story."
Next came her heroine Eve, she said.
"Even though I'm writing a twisty, plot-driven thriller, it was really important to me that the book have heart and be sort of grounded by this character, Eve, who starts off so vulnerable, but then discovers that she's pregnant and discovers a new strength because she's a mother, she's got to become a kind of fierce Mother Bear, because she's going to be put in a very dangerous situation."
The extent to which the wealthy exert power is a key theme of the novel, she said.
"How they make use of their power, their knowledge and their prestige to get their own way and bulldoze over other people
"This is something that's getting a lot of attention at the moment. I've certainly noticed among young people, there is a sense of anger at the billionaires of the world, the super wealthy elite, and how they use their power to have outsized influence on the rest of the world."
Carlyle said she inhabits her characters when she is writing.
"My children say, 'oh, Mum's got a book hangover'. Because after I've been writing, I'm still so much in the head of my character that I sort of can't come out and relate to normal life, and I don't hear them speak to me.
"So, I do find myself almost imagining that I am the character. Both of my characters have been left-handed, and I'm not, but I find myself reaching for things with my left hand, because I'm so inhabiting their minds that I almost forget who I really am."
The success of Girl in the Mirror was life-changing, she said
"I was able to give up my day job, which was just beyond my wildest dreams, and start writing full time. With No One Will Know, I had that luxury of time and being able to really work through what story I wanted to tell and make sure that I got it right before bringing it to readers."
Meanwhile she's enjoying the freedom that brings.
"What I want to bring to readers, is that sense of fun. I mean, I actually really love those really serious literary works that New Zealand is known for, and that have put us on the world stage, ever since The Bone People.
"But I think there's also a place for books that are just entertaining and exciting and page-turning. And I think maybe, as in New Zealand fiction, we have kind of neglected those at times."
A plot-driven novel can effectively explore deeper subjects, she said.
"I don't want the reader to feel like they need therapy after reading.
"I want them to enjoy the ride, it's exciting, but it's not disturbing and not grim."