One minute, a young mother is walking home with her five-year-old son. The next, he's dead, hit by a car after letting go of his mother's hand to run ahead. As if the situation weren't nightmarish enough, the driver takes off without stopping.

Detective Inspector Ray Stevens of the Bristol Criminal Investigations Division catches the case, along with his junior officer, Detective Constable Kate Evans. Though Stevens has developed coping mechanisms to deal with the heartrending situations he encounters at work--"If he thought too long about how it must feel to watch your child die in your arms, he would be no use to anyone"--Kate, new to CID, is upset by little Jacob's death.

Jenna Gray is also shattered by the car accident. Mourning her son, she leaves her house one day and hops on a bus with no destination in mind, wanting only to get lost. She ends up in a remote Welsh seaside town called Penfach, rents a rundown cottage, and starts rebuilding her life where no one knows who she is or anything about her devastating past.

Months pass, and there's still no arrest in the hit-and-run that killed Jacob, despite all the attention it receives, with the little boy's picture splashed on the front pages of newspapers. Though long ordered by the chief constable to close the case, Kate keeps working on it on her own time, and eventually convinces Ray to review the old files, too. Then, to mark the one-year anniversary of Jacob's death, the police make a public appeal for any new information. 

The appeal results in a tenuous lead for the car, but Ray and Kate work it until they have a solid clue about the guilty driver's identity. What happens next upends Jenna's life, for nothing is as it appears, and the cops find they're far from closing the case.

It's hard to believe I Let You Go is Mackintosh's debut novel because it's so assured. From plotting to characterizations, the author skillfully takes readers inside the frustrations of police officers trying to solve a high-profile case with very little information to go on, and on the flip side, what a mother's grief looks like when she loses a child. Jenna's ordeal is raw, but she's a riveting character, at once fragile and resilient, from whom it's hard to look away. Readers will be fully invested in the emotional journey she goes on, keenly feeling her open wounds and tentative hope as she tries to forget her past and move on.

Ray and Kate are engaging characters, too, providing the yin and yang of the investigation--he the veteran rediscovering the hunger he used to have as a young detective ("I like to have [the victim's photo] where I can see it.... Where I can't forget what I'm doing, why I'm working these hours, who it's all for"), and she the newbie whose idealism lights a fire in her senior partner. She also sparks feelings in Ray that aren't entirely platonic, which is problematic since he's married with children. (How Kate handles the situation is refreshingly free of neuroses.) To add to Ray's turmoil, it seems his son is being bullied at school. All this provides well-rounded pictures of the police behind the procedural and realistic rhythms in their dialogue, perhaps owing to the fact that Mackintosh spent 12 years as a police officer herself.

There is a third narrator who adds a whole new angle to the case, but saying any more would spoil the story.

The author doesn't just conjure up memorable characters and gripping plots; her settings ring true. Penfach--with the cliff-strewn coastline--and its people are warm and hard, breathtaking for their beauty and harshness. It makes perfect sense for Jenna to choose it as a place to run away to, someplace that might allow her to heal but perhaps not let her forget the jagged edges of her pain. Mackintosh is also very good at keeping readers ensnared in suspense. The most impressive feat Mackintosh pulls off is the bombshell that's on the level of the movie The Sixth Sense for its cleverness. Readers who say they saw it coming are most likely fibbing. The revelation is so good, readers might want to reread I Let You Go to see how it changes their perceptions--even the title takes on different interpretations--and whether or not the twist holds up. It does. This kind of sharp, cunning writing makes one eagerly look forward to Mackintosh's next novel. --Elyse Dinh-McCrillis

photo: Smart Photography

Clare Mackintosh spent 12 years on the police force before she published I Let You Go, the debut novel that became a runaway bestseller in the U.K. and has been translated into dozens of languages. Berkley is releasing the psychological thriller in the United States in May 2016. Mackintosh talks to Shelf Awareness about her book's astounding success, the scenes that were hardest to write and what the phenomenal reception for her debut means for her follow-up.

One of the buzziest things about your book is the gasp-inducing twist. Was that planned from the start, or did it come to you as you went along?

The twist was the first part of the story that came to me. I knew exactly what I wanted to do, the effect I wanted to have on the reader. Without giving too much away, I wanted to challenge the assumptions we all make about people, and bring in some of the grey areas that exist in real life, in real people. It was technically quite a difficult part of the story to pull off, and I will never tire of hearing readers' reactions!

The story deals with the grief of a mother losing a child--something that's happened to you. Was it difficult or cathartic to write about that?

My son died when he was five weeks old. It was, and still is, the hardest thing that has ever happened to me. I found some of the scenes in I Let You Go exceptionally difficult to write, and extremely emotional. There would be times when I would be sitting at my keyboard, tears streaming down my cheeks, wanting that particular scene to be over. It was just too raw, too real. But overall I think I did find it cathartic, just as I have always found it therapeutic to blog about the way I feel.

The novel has different narrators. Which voice was most fun to write? Easiest? Hardest?

There are three narrators. Most of the story is told through Jenna, who escapes to a remote cottage in an attempt to come to terms with her past. We also see the story from DI Ray Stevens's point of view, as he and his colleagues work to trace the driver of the car that killed five-year-old Jacob.

I enjoyed writing from both perspectives; it was great to draw on my police experience to write Ray's chapters, and I felt so emotionally invested in Jenna's character that it was a joy to write. The third narrator--it's impossible to discuss this in any depth without spoiling the plot--was difficult to write, simply because I didn't want to spend any more time in their head than I had to!

How has your experience been as a published author? What was the biggest surprise post-publication? How did you celebrate when your first rave review came in?

I've been incredibly lucky. I have a great agent, the wonderful Sheila Crowley at Curtis Brown, and amazing publishing teams in the U.K. and the U.S. I remember reading somewhere that if a debut novel sells 20,000 copies it's done okay, and thinking that seemed like an awful lot. I couldn't imagine ever selling that many.

I Let You Go has now sold half a million copies in the U.K. and has been translated into 26 languages. It's an absolute dream come true. The biggest surprise was finding out I'd been picked as a Richard & Judy book club read, which meant meeting two of Britain's best known book-club champions, and seeing I Let You Go in every airport and train station in the U.K. It was amazing. I'm rather embarrassed to say that there have been so many celebrations, I can't remember how the very first one played out.

You used to write an advice column on law and forensics for Writing magazine. What's the weirdest or most disturbing question you were asked there?

I loved writing this column. Mostly readers would ask things I knew the answer to, but I've been asked all sorts of questions about mounted police, helicopter pursuits, ballistics and more. Fortunately I have great contacts with serving officers who were happy to help me with the answers. The most gruesome question was about the degradation of human flesh when dissolved in acid. It's enough to put you off your lunch!

You've mentioned that real police officers, unlike fictional ones, address each other by first name instead of title and last name. What are some other details most crime novels don't accurately reflect?

I'm very tolerant about procedural inaccuracies in fiction; crime novels would be very dull indeed if they adhered too closely to reality. That said, I always find it hard to swallow when U.K. police brandish guns about, or keep their police cars at home, or charge people they haven't even interviewed yet. It suggests a lack of research that takes me out of the story.

Who are some of your favorite fictional detectives?

Sarah Hilary's Marnie Rome is a great authentic contemporary detective, but I think my favourite investigator of all time has to be Agatha Christie's Poirot, and not just for the great moustache.

Tell us about the Chipping Norton Literary Festival, which you founded, and some of your favorite experiences that have come out of it.

When I left the police in 2011, I was worried I'd be bored without a department to run. I set up ChipLitFest with some like-minded local people, with the aim of creating a community project that had national reach. We've had some fantastic authors--Lionel Shriver, Peter James, Brian Blessed, Joanne Harris--and last year we became the first literary festival to divide its profits equally between all the authors involved in the event. I'm hugely proud of it, and honoured to remain a trustee, although the hard graft is all done by other people nowadays.

How has booking authors and being on the receiving end of pitches informed how your reps book your author appearances now?

It's been interesting being on both sides of the fence. It's made me keen to support smaller festivals, and very understanding of the budget constraints they experience. I love doing events and enjoy small audiences just as much as big ones, often more.

The first book you wrote was, by your definition, chick-lit. Might you go back to that genre someday?

The first book I started was called Baguettes and Brothels, about a British girl in Paris. I saw it as a sort of contemporary Down and Out in Paris and London, which was a bit optimistic of me, I think. I never finished it. I got serious about writing in 2010, when I wrote a chick-lit novel called Hot Property. It was quite funny, and brought me to the attention of a literary agent, but the story wasn't strong enough and when I started writing I Let You Go, I knew I'd found my niche. I'd never rule out writing in any genre, but for now psychological thrillers are where I am.

Does the huge success of your debut novel make you feel more confident about the second book, or does it create more pressure?

Oh, it's terrifying! With I Let You Go, there was absolutely no pressure. My deal was relatively small, which meant I didn't feel the weight of expectation from my publishers, and there was no prepublication hype from the U.K. media. The book's success crept up gradually. There was online buzz first of all, on Twitter and Facebook, and it just got bigger and bigger. With my next book, I See You, I feel under enormous pressure to deliver something just as good, and it's hard not to let that get to me. I try to focus on simply writing the best book I possibly can. I can't do any more than that. --Elyse Dinh-McCrillis