(dramatic music) - Well, the golden age of Detective Fiction is an inherently British thing.

I think there are claimants from all around the globe.

There are certain American aspects to it, but what we think of as the murder mystery is absolutely quintessentially British, despite empire and cricket and all sorts of things.

The one thing we can definitely claim we invented was a proper murder mystery.

(person laughing) It's our greatest export, murder.

So in "Moon Flower", despite the fact that we start in Greece with Susan starting a completely new life with her boyfriend, when she's drawn back, it's to England and to a country house hotel for a quintessentially British murder.

The detective duo starts with Sherlock Holmes, Dr. Watson really, and everything else is, you know, a line drawn from there.

And I think a lot of people have tried very hard to do something different with that formula.

But there is something obviously just innately useful about it.

Every detective needs someone to talk to.

Everyone needs a Watson, as it were.

The question is what to do with that character.

And also, again, what Anthony's done very cleverly is Punt is his own detective.

But because in Susan's head, she becomes his Watson, as it were.

There's a golden period flowing from Arthur Conan Doyle, right the way through to the Second World War.

And there are dozens of great writers, not just Christie, like Christianna Brand who had a Inspector Cockrill was her detective, Dorothy L. Sayers with Lord Peter Whimsy.

Christie obviously with Poirot and Miss Marple.

And it was so popular, everyone had a go and everybody wanted to cash in on it.

Hundreds of them have been totally forgotten, but you find real gems.

I'm a big fan, the British Museum have started publishing lots of lost ones from between the wars and there's some really lovely stories.

Very clever, and what makes a great mystery?

Well, I mean, that is the question.

If it was an easy answer, everyone would do it.

I've got a great story about this.

Billy Wilder, one of the greatest directors of all time, he made a movie of Agatha Christie's, "Witness for the Prosecution" in the fifties, a fantastic film.

He was interviewed about it and he said, listen, my friend Agatha Christie's characters, her dialogue, I could write it an afternoon, but her plots are like ball bearings.

(person laughing) And that's the essence of it.

And the reason that someone like Christie survives because her ideas are absolutely amazing.

Ultimately, I think you have to have a really clever murder.