- When we first went to a very major broadcaster in the United Kingdom, they dismissed it with a single word.

It's unadaptable.

To her credit, the producer, Jill Green, did not give up and nor did I. And we start to think about how these books would be adapted.

- Susan Ryeland and Atticus Pund make an effective detective duo.

- What I like about this is the Pund/Susan relationship is delightful.

- The world that Anthony's created where these mysterious things happen.

Every time Susan gets stuck, he appears.

It's like an internal dialogue that she has with herself.

- Nobody could take the novels, which are written as two absolutely separate stories.

Only he could weave them together.

- I got a quarter of the way through it and my mouth was open with how anybody can weave this extraordinary tapestry of characters.

- And how to make it all work on the screen was an enormous challenge.

But for me, the most exciting moment was the breakthrough.

And we realized that if we ran it not as two stories one after another but two stories side by side, we would create something that had never been done before.

- You sort of have to imagine what's happening in your mind as you read it.

And you adapt what you imagined to the place that you're in.

And that only works if the place that you're in is right.

And then the same is true for casting.

You imagine somebody.

But then you meet someone and you think, "Oh yes, they can do that."

With most of our characters, they're playing two roles.

- I love the double casting as well.

I thought that that was really clever and a great opportunity for actors to show their stuff.

- I would love to be one of those actors, you know, in a parallel universe playing those two characters.

Because, you know, you play, in a sense, the real person in the real life.

And then you play a slightly unhinged version.

I think that's such a great opportunity for an actor.

I'm quite envious of the people doing it.

- Most brilliantly for us as an actor, it's the fact that you're getting to play these two characters in these two separate worlds.

- It's a very different kind of challenge, but it's great.

I treat them as two different jobs in a way.

- Well, it is two different jobs.

- The Miss Marples and the Colombos of yesteryear are being re-imagined in a really brilliant way.

The story within a story, the intricate nature of the narrative and how the characters merge makes for very good telling.

- The crew, the people, Rebecca, the director.

- Yeah, it's so happy.

- Anthony, Jill, you know, it's a really, it was one of the happiest jobs I've ever done.

- Me too.

(light orchestral music)