HER murder mysteries are adored the world over because they are so quintessentially English — in that reassuring, unthreatening Sunday night TV kind of way.
There is something benign and comforting about a good Agatha Christie yarn, the nostalgic retro styling evoking an age that was glamorous and somehow cosier and safer.
Only of course the "safer" is debatable. For beneath the charm of the old country houses, there usually lurks an unsettling fact: all of Christie's murder mystery victims tend to be intimately known to their killers. Husbands kill wives, children kill parents, siblings kill each other.
The real answers to the puzzle of conflicting evidence, it would seem, lie not in railway timetables or false identities but in the darker side of human psychology. However, before viewers get too rattled, there's a characterful detective on hand to make sure that fair play triumphs over felony.
"They are real little puzzles," says Sophie Ward, who plays Carla Le Marchant in Agatha Christie's Go Back For Murder, heading to the Queen's Theatre next week. "Most of us read them when we were teenagers and they were some of the first crime books we read. I don't think you ever get that out of your system, the impact that her books make on you."
Christie may have her detractors but one thing is for sure: nothing seems to get rears into theatre rows quite like a traditional whodunnit from Devon's queen of crime.
"They have a venerable history," says Sophie who starred in the TV version of Agatha Christie's Miss Marple: A Caribbean Mystery.
"They have been filmed so beautifully for TV with such an amazing cast."
Sophie isn't surprised that theatre audiences across the UK lap them up.
"Christie is one of the biggest selling names in the world. Everybody knows who she is and there is instant brand identification. Her name is like a guarantee of quality."
Sophie, who many will know as Elizabeth Hardy in Young Sherlock Holmes, has what she describes as a "nice juicy part" in Go Back For Murder.
"I play Carla Le Marchant who comes over from Canada to England. She's been told that her mother died in prison having been accused of killing her husband. Carla has come back to clear her mother's name, 20 years later."
Sophie actually plays two parts in one: in the first half she's Carla and in the second half she plays Carla's mother, Caroline.
"The first half is set in the Sixties. Carla, especially because she's from Canada, is rather cool, relaxed, confident and outspoken. In the second part I play her mother who is much more reserved, English, and post-war. They are quite a bohemian family, though, and a fun household."
As always the show promises to be a nostalgic period drama with plenty of retro styling.
"It's quite fun in this show because we've got the Sixties thing and we've gone for some iconic Sixties dresses. People will recognise those mini dresses and it has quite a stamp of that period plus the Sixties music."
Sophie is joined by a star-studded cast that includes Robert Duncan, Liza Goddard, Lysette Anthony, Gary Mavers and Ben Nealon.
Go Back For Murder by the Agatha Christie Company is at the Queen's Theatre, Barnstaple from Monday, April 29 to Saturday, May 4, 7.45pm. Thursday and Saturday matinee: 2.30pm. Tickets: £16 to £23. Box office: 01271 324242.