Hercule Poirot sleuths again in Sophie Hannah’s The Monogram Murders: The New Hercule Poirot Mystery.

When did you first encounter Agatha Christie?

I first read her at the age of 12, when my father bought one of her books for me at a second-hand book fair. It was The Body in the Library, and I just adored it. I immediately sent him out to more second-hand book fairs in search of more Christies (I was quite a bossy 12-year-old!), and, by the time I was 14, I had a full collection of battered paperbacks—all the Poirots, all the Marples, everything—and had read them all at least once. I became a lifelong Agatha addict.

How would you assess her legacy?

Agatha’s impact on the genre is immense. First, there’s the fact that she’s the very best at it, an ever-present example of what we could and should all be aiming for. From a puzzle-and- solution point of view, no one has ever surpassed her. And her continuing massive popularity emphasizes the importance of those aspects of the genre that she underlined in her work as mattering most: palpable love of storytelling above all else, that perfect combination of pleasurable ease in reading with a tough intellectual challenge in every book, the importance of motive—both Poirot and Marple talk constantly about psychology—and the impossibility of understanding anything without it.

How does the book compare with your own series?

The Monogram Murders is similar to my regular Simon Waterhouse and Charlie Zailer novels in several ways, but that’s probably because I was so heavily influenced by Agatha from the start. I have tried to offer readers all the things she provided for me as a reader: 1) an apparently impossible how-can-this-be-happening opening mystery, 2) a totally unguessable solution, 3) a super-brilliant detective who is much, much cleverer than everyone else and always gets it right, 4) motive as the most important thing: the last prize to be unwrapped at the end of the story, and the one that makes it memorable and worthwhile.

What was it like writing the book?

What surprised me most while writing The Monogram Murders was that everything I needed seemed to arrive in my head exactly when I needed it. I started out with only two ingredients: Poirot, obviously, and a solution to a mystery that I thought was ingenious. I was very daunted (as well as honored) by the prospect of... well, not so much stepping into Agatha’s shoes, because nobody could do that, but of polishing her shoes, shall we say?! But I was scared, too. What if I couldn’t do it? The great thing was, though, that before I had a chance to start worrying seriously about this, every single ingredient I needed, as well as a weird feeling that I probably could pull it off, arrived as if by magic.