Meet the Author: Kate Mosse
25 October 2012 Last updated at 20:16 BST
Author Kate Mosse has published her final instalment of a trilogy that was inspired by French history.
Mosse said Citadel was based on years of researching "hidden history" in France.
In this week's Meet the Author, Nick Higham spoke to Mosse about her follow up to Labyrinth and Sepulchre.