Where did you get the idea for your most recent book?
This question seems to imply that inspiration for a book would come from just one source. That's madness! Inspiration for Riddle of Regicide came from so many different things that it would be impossible to list them all. However, if I had to come up with a list, I'd say the mystery portions were inspired by Harlan Coben novels, while the fantasy world was influenced by classic RPG computer games.