JP: First of all, that is so incredibly nice of you to say. This is really crucial for your stories, which often require characters to work together as a team. Not only that, but you also are able to have them interact with each other in an authentic way. TSL: In every single one of your books, you are able to create dynamic characters with distinct personalities, making them so real that they almost seem to leap off the page. A good friend of mine is Stuart Gibbs, whose Spy School books are hugely popular. Currently there are many great spy and mystery writers who influence me. That book as well as her others has always influenced my writing. JP: When I was growing up, my favorite book was From the Mixed Up Files of Mrs. TSL: What authors or books have had the greatest influence on your writing, especially for this book? The first thing I figure out when I write them is what cities will be in this story.

The first part I came up with was give the spies code names based on the cities they were from and it just grew from that. I also wanted to set it in great cities on different continents. Everything about the cities was exciting and it made me want to write an international story with kids from around the world. We went to London and Paris and had the best time.

James Ponti: My wife and I went to visit our son who was studying in England for the year. How did that tiny idea develop into City Spies?

Thee Sim Ling: I read that a vacation in Europe first inspired you to write this series on juvenile secret agents. Luckily, the bestselling author of the City Spies series generously agreed! Below is their conversation, where they discuss writing about different cultures, literary influences, favorite characters, and more. Editor's Note: Recently, Stone Soup blogger Thee Sim Ling reached out to us to ask if she could arrange an interview with one of her favorite authors, James Ponti.

City spies book