(gentle music) - [Kacey] With this show, the female characters are really strong, and we really wanted to show a story that could reflect on what was happening then and how far we've come.

- [Staff] Good morning, Mr. Harrison.

- Winning smiles.

- I've often suggested storylines to do, and it's brilliant because the production company are really open to that.

So then we came to be doing series nine, and they said, would I like to come on board to help story it and write some of it, but also being kind of mentored by Daisy Coulam who's our head writer, which was just an incredible experience.

As an actor, you don't see a lot of the stuff that goes on pre-production.

So, absolutely brilliant to be able to be part of all of that.

- Kace was writing this series, so she brought lots of ideas.

One thing she wanted to explore was the women of "Grantchester."

- That poor girl.

I don't know how you handle it.

- I could say the same for you.

The kids, the house, the husband.

I have to say it never appealed.

- (sighs) I haven't been handling it lately.

- It was really important for me when we were storylining episode five, that we did focus in on the female angle.

- It's for contraceptive pills.

- [Esme] They're in a handbag.

- The characters have grown over the years.

And also, we have such a brilliant age range, where we can be looking at how the world is changing and how they're trying to fit into that world.

- [Daisy] We go into Esme's the world of work, the sort of "Mad Men" style office.

- New girl, nice top.

- And Geordie has to confront that his little girl is now being thrust into this world of predatory men and he can't protect her anymore.

- You have no idea what happens in places like that, with men like that.

- You're jumping at every shadow.

You're starting to sound like your mother.

- Cathy's going through a bit of a time.

I think she thinks she's losing her mind.

- A few years back, we had a storyline where Cathy's mother had mental health issues, and Cathy feels like she's headed in her mother's direction, and is frightening to her.

- [Doctor] Mood stabilizers.

- [Cathy] I don't wanna end up like her.

- You're not mad, Cathy Keating.

- It's a really wonderful episode.

It's really, really exciting when I was told that it was gonna be very female-driven.

- You're keen.

- Hmm.

How do you think the filing gets done?

- And obviously I was even more excited to find out that I was gonna leave the police station and solve the case.

- One of those girls knows something.

I could get her talking.

- I go undercover.

When I found out I was going undercover, I was like, "This is amazing."

- It's been a brilliant exploration, and it's so wonderful that this show is able to do that because the characters have developed and are rounded, and are full.

- To men.

I'm kidding.

To us.

- To us.

(Cathy chuckles) (glass clinks) (dramatic music)