As well as having a ‘what if’ question that acts as the spark of an idea, there’s another element that’s vital for me in order for the spark to catch light – the setting.

From empty, windswept beaches to dark and creepy woods, getting that sense of place is essential. With The Woman in the Dark, as well as the eeriness of a seaside town out of season, the Murder House itself became one of the characters – almost living and breathing and influencing the story as much as the characters themselves.

It was the same with The Woods – I had the characters and my ‘what if’ question, but the ideas were just drifting until I took my own walk in the woods with my family. Looking back later at the photos I took of my daughters, the setting started to unfold in my mind and the story came to life with the fairy tale line that’s repeated in the book: Once upon a time, two girls went into the woods, but only one came out… Before writing my first book, I worked as a designer and illustrator and I think I still need that visual imagery, that sense of place, to be there from the start.

Realising that has made researching future books so much easier – I take photographs, save images that make me smile, that haunt me, that give me a sense of peace or a shiver of unease. The Night They Vanished is set in both Cardiff and the same stretch of fictional coastline as The Woman in the Dark and The Woods. The holiday park which is mentioned in passing in my first two books takes centre stage in The Night They Vanished, with Hanna and Sasha brought up surrounded by all the noise and colour, but very much apart from it, outsiders in their own home.