After a decade and 17 books, Caroline Lawrence finally brought her Roman Mysteries series to an end this year, but is already beginning to work on a spin-off.

The American, who lives in Battersea, will be talking to children about the art of writing mystery books as part of Polka Theatre's annual book festival The Word on Saturday week.

Her books following the lives of four crime-solving children in the Roman Empire proved so successful they were made into a series for CBBC but despite the time she spent on them, she was far from sad when penning the final sentence of the final book, The Man from Pomegranate Street, which came out in June.

"It was one of the biggest highs I have ever had," she said.

"A because I finished it, B I married off my two girl characters and C I left it in a way that you still feel the mysteries are going on and that I could maybe one day write another story about them.

"I am hoping to do a spin off for younger kids.

"I haven't even got a name for it yet but it will be set in Ostia in Rome again but aimed more at the seven to nine year old group."

The Word festival is part of Wimbledon Bookfest which begins on Saturday, and is something Lawrence has wanted to be a part of for a long time.

"I have been wanting to be involved for about seven years so I'm really glad to get the opportunity this year," She said.

"My talk is called How to Write A Mystery and I will be telling the kids about my three favourite things in the world, writing, watching television and going to the movies.

"I plot my books using Hollywood screen writing techniques, the way they plot the movies, using the seven elements of story structure which is easy enough for kids in year three to understand but still got me published.

"When you are talking to kids I never do a reading because it's too static, it's best to get them on every level.

"I will be talking, moving around, showing artefacts, clips from films and there's a chance for a Q&A at the end as well where they can ask me any questions apart from two I always get in Holland - how old I am and how much I weigh in kilograms."

Program for The Word:

11am: Roger McGough - The patron saint of poetry amuses with his warmth, wit and wordplay.

11.05: Leigh Hodgkinson - The animator and illustrator presents storytelling and craft activities.

12.30: Polly Dunbar - The Flyaway Katie author offers stories and drawings from her Penguin and Tilly series.

1pm: The Utterly Inventive World of Roald Dahl - David Wood OBE has adapted many Roald Dahl classics and will talk about the storyteller and turning his stories into plays.

2pm: Marcus Sedgwick - The writer of The Raven Mysteries tells all about his characters.

3pm: Caroline Lawrence - The Roman Mysteries writer gives advice on writing mysteries 3.30pm: Glitterwings Fairy Party - Come in your best fairy outfit for fun, glittery games and plenty of pretty prizes with author Titania Woods.

The Word, Polka Theatre, The Broadway, October 10, 11am - 5.30pm, £5 for one event or £8 for two or more. Call 020 8543 4888 or visit polkatheatre.com.