Tana French's Dublin murder mystery novels, of which the new release The Secret Place is the latest, always hit the bestseller lists. But her readers are a proud cult in my experience, always happy to find another fan to discuss them with. She has a talent for lighting up the brain's pleasure and intelligence centers.

French first introduced us to a Dublin full of jaded detectives with In the Woods, which came out in 2004. That book wove two mysteries together, both murders committed in the same woods twenty years apart. The first, a disappearance really, was never solved. And one detective called in to investigate the second, Rob Ryan, turns out to have been the sole surviving witness to events twenty years ago. Except that he could never quite remember what happened to him in the woods.

The woods are actually a good metaphor for the rest French's work. It's a tangled sort of place, and with every book the brush gets thicker. A different Dublin detective narrates each novel, but they're all linked and have appeared in a previous book. French manages to give them different voices, and ways of thinking. The books are all doubtful about the possibility of getting at the one single truth of a crime, and certain about the impossibility of objective investigation.

The Secret Place, the latest, finds a young detective, Stephen Moran, hoping to make his way onto the murder squad. Moran gets his chance when a young woman named Holly Mackey brings him a tip about the murder of a young man at her girls' school. Holly, it just so happens, is the daughter of Frank Mackey, who narrated French's third novel, Faithful Place.

French answered a few questions for us by email about her career, and The Secret Place's role in it.

You get described a lot as someone who's taken the detective genre to "another level." Do you agree that's what you're doing?

I think I'm part of a wave of writers who love mysteries and who don't see any reason why we, or our readers, should be told "Mystery novels must do this and no more." I've never been much for the artificial divide between "literary" fiction and "genre" fiction. You still occasionally get the tired old clichés about genre fiction being badly written and full of one-dimensional characters, and literary fiction being plotless and meandering, but that's more and more obviously silliness. That perceived genre barrier is disintegrating, and I love that. I've never seen why audiences should be expected to be satisfied with either gripping plots or good writing. Why shouldn't they be offered both at once? Whether I actually manage to offer them both (or either) is a whole other question – but that's what I'm aiming for.

And in that context, I think I started writing at the perfect time. In the 1990s, the mystery genre opened up. People like Laura Lippman and Dennis Lehane were writing mysteries that had gripping plots and complex characters and beautiful writing and social depth. Donna Tartt blew the boundary between crime fiction and literary fiction wide open with The Secret History. Writers like John Connolly and Michael Gruber were bringing supernatural elements to a genre that had mostly been very firmly tied down to the naturalistic. By the time I started writing In the Woods, in 2004, the whole genre looked very different from the way it had fifteen years earlier; there was space for new things to happen within it. There are more and more wonderful writers – people like Gillian Flynn, Kate Atkinson, Stef Penney – who are breaking down the mystery genre's old boundaries, carving out new zones for it, making readers see it in new lights. I hope I'm a part of that.

Who would you describe as your influences?

I think all my deepest influences are books I loved as a child or as a teenager. Those are the books that shape your whole image of what writing can do, what it's for; you never get away from them. The way Richard Adams creates atmosphere in Watership Down; the flawless rhythms of Mary Renault's prose; the sheer gut-punch perfection of just about everything Dylan Thomas ever wrote; the struggling, complicated humanity of T.H. White's characters in The Once and Future King; just about every aspect of To Kill a Mockingbird… Those are all things I've been in love with for more than half my life. I may never get anywhere near their level, but those are the ideals that are somewhere at the back of my mind when I'm writing. More generally, I loved time-slip books when I was a kid, books where the main character somehow ends up a few centuries in the past or sharing the present with someone who's slid in from another time – and although I don't actually write about time slips, those childhood books show through in mine. I'm still fascinated by the liminal, by boundaries that turn permeable for the right person at the right time, by the points where reality ceases to feel quite so neatly defined.

Do you have a writing routine? What is it?

Ha. I wish. Up until last year I had a nice smooth routine where I wrote for six hours a day, but then I had our second baby and I haven't managed to get the extra chaos under control yet. I still write every day, weekends and all, but I never know what hours I'm going to have for writing. If I'm good in this life, next time I get to come back as someone with decent organizational skills.

How do you come up with all these ideas for these crimes? Are you a fan of crime shows? Do you read a lot of tabloids?

Weirdly, none of my ideas have ever come from actual crimes, or even from anything crime-related. I think it's because it's not murder, or even crime in general, that fascinates me – it's mystery. I've always loved mysteries, ever since I was a kid – real ones, fictional ones, solved or unsolved, I don't care. I write about murder because it's one of the great mysteries of the human heart: how can one human being deliberately take another one's life away? That's why I don't usually write evil villains: there's no mystery in why an evil person would do something evil. The mystery is what could bring a normal person, someone who's capable of empathy and love and who isn't innately cruel or destructive, to that point.

So I'm always looking for the potential mystery in everything, which means I end up finding ideas in really ordinary things. The ideas for my books have come from, in order: a wood near an archaeological dig where I was working, a pub conversation about doppelgangers, a suitcase in a skip, the time we had mice in our flat, and – for The Secret Place – a website called PostSecret, where people send in postcards revealing their secrets anonymously. Each time, I started wondering how that small thing could be a way into a mystery, and gradually that question turned into a book.

I can't help but notice how stuck you are on Frank Mackey's charisma. (I am too.) Why do you keep coming back to him?

I wasn't planning to! When I started The Secret Place, it was Holly, Frank's daughter, who I had in mind. I liked her in Faithful Place, where she's nine: she's smart, devious, loving, strong-willed and independent, and I thought that combination would probably make for an interesting teenager. But yeah, I was happy when I realized Frank would inevitably show up during this investigation. He's a lot of fun to write.

What I enjoy about Frank isn't so much his charisma as his certainty. He's absolutely clear on his priorities, and totally ready to sacrifice anything that's low on that list for the sake of something that's higher up – so in The Secret Place, for example, when he thinks his daughter is in danger, he doesn't think twice before doing his best to throw Stephen and Antoinette and their whole murder investigation under a bus to save her. Most people put a certain amount of time and energy into struggling with questions of morality – if I have to make a complex decision with big moral implications, I'm going to put time and thought into trying to figure out the right thing to do, weighing up my own desires against what I think is right, going through all the implications… It's fun to write someone who has zero time for that crap: he knows what's important to him, does his utmost to blow away anything that endangers it, and then keeps going without a second thought. It's also very interesting to write about what happens when someone like that has his certainties ripped away, the way Frank does in Faithful Place.

This leads me to ask, of course, if you're going to come back to Rob Ryan. I was talking with another book critic about your work and we mutually expressed to each other a secret hope that you'll get back to him someday, perhaps when we're all older and grayer and blessed with many more of your books in better. Any chance of that?

I'd love to go back to Rob Ryan. If I ever get the right idea that would let me pick up his story again, I'll dive on it. So far it hasn't happened, but I'm hoping.

[Phot of Tana French by Kyran O'Brien.]