It was that creepy atmosphere in the village and forests of Rennes-les-Bains in south-west France that proved an inspiration for her latest blockbuster novel Sepulchre.
The absorbing adventure story about ghosts, tarot cards and Visigothic tombs in 19th century and present-day France was only published in paperback by Orion Books on May 15.
But it looks set to be another bestseller for the Chichester author.
Her last novel Labyrinth – a Holy Grail quest set in medieval and present-day France – enjoyed enormous success in 2005. After winning Richard & Judy's 'Best Read' at the 2006 British Book Awards, Labyrinth sold 5m copies, and has been translated into 37 languages and published in 40 countries.
Although she's not yet in the same league as Dan Brown (The Da Vinci Code sold more than 60m copies) and J K Rowling (the seven Harry Potter books have sold more than 400m copies worldwide), her success is remarkable in an industry where sales of 10,000 are considered good.
Early sales for Sepulchre suggest she has another hit on her hands as more than 250,000 hardback copies have been sold worldwide in eight weeks.
Kate still finds success hard to take in. 'It's a mixture of luck and timing,' she said. 'There was a public appetite for this type of novel when Labyrinth came out. Being picked for Richard and Judy was enormously important and that's being carried over for Sepulchre.
'You do have some nervousness when a book comes out. But I've had some good responses.
It's not just her book sales that have increased. Her profile has also risen.
She's a guest presenter for BBC Radio 4's Saturday Review and Open Book, a book reviewer for BBC Breakfast News and for Simon Mayo on Five Live, and is regularly featured in national newspapers.
She's also the co-founder and honorary director of The Orange Broadband Prize for Fiction awards.
Not bad for a former Chichester High School for Girls pupil brought up in the small village of Fishbourne.
The key to Kate's success is location. The source for Sepulchre was the spa village of Rennes-les-Bains in south-west France – 20 miles south of Carcassonne which inspired Labyrinth.
The 46-year-old said it was complete serendipity that she and husband Greg bought a house in Carcassonne two decades ago.
The mum-of-two said: 'It was chance. We only looked at Carcassonne because a friend knew an estate agent there. It was a case of looking at brochures and Greg going down to buy a place. I couldn't even go before we bought the house because I was pregnant.
'I've always thought "what if our friend knew an estate agent in Cardiff?" Would I have still written?'
The family used to spend six months of the year in France, but her children's studies mean Carcassonne is more a holiday home now.
Daughter Martha, 18, is busy swotting for A-levels at Havant College while son Felix, 15, is studying dance and GCSEs at the Arabesque School of Performing Arts in Chichester.
Husband Greg, who grew up in Leigh Park, also has work commitments as a lecturer at West Dean College near Chichester, where he founded a creative writing programme.
Last June the family moved from Bognor Regis to a large home in Chichester. 'I'm passionate about Chichester,' Kate said. 'I went to school here and when we lived in Bognor we always felt Chichester was home. I even say "Chidester". which is a bit of a give-away if you're local.'

Win Kate's new novel

We've teamed up with Orion Books to give away five copies of Kate Mosse's book Sepulchre. We also have a pack of limited edition Sepulchre postcards to give away with each book.
To win, just answer this question:
Kate Mosse's first blockbuster novel was called Labyrinth. But according to Greek mythology, where was the labyrinth that was built to hold the part-man part-bull creature called the Minotaur?
There are four ways you can enter. The closing date is midday on Tuesday, June 3, 2008.
E-mail to promotions@thenews.co.uk under the title 'Kate Mosse Competition'.
Write your answer on a postcard and send it with your name, address and daytime telephone number to: Kate Mosse Competition, The News Centre, Hilsea, Portsmouth, PO2 9SY.
Send a text message starting with tncomp katem, the answer to the question plus your name, house number (or house name) and postcode to 81800.
Example of message: tncomp katem answer john smith 1 po2 9sx