Emilia Fox, David Caves and the Lyell Centre team discuss series 27 as the BBC Studios produced crime drama returns for five more two-part mysteries on BBC One and Player.

How are Jack and Nikki getting on in this series?

They are going strong. A big thing last year was that we didn't want to make it a bickering adolescent type of relationship - which we could easily have done. But it is different with Jack and Nikki. We are seeing them working together, and their relationship does not seem to be interfering with their work. They're professional, and they simply get on with their work. But they have moments where they check in with each other and then little subtle things that happen between them to let people know that they're still very much together. I can't really go into much detail, but there's a nice progression in this series. It comes to a nice crescendo, if you will. And so I hope people are pleased because Jack and Nikki have some lovely moments together.

Does their very stressful job heap pressure on them?

Yes, especially in the latter episodes of this series. There is an episode called Kings Cross, which is a biggie. It’s probably the most we've had to shoot ever. It’s very intense. The case involves eight bodies being discovered under Kings Cross. That means Jack and Nikki have to do eight post-mortems and not cross contaminate. So it's a very, very big couple of episodes for them. It's stressful, especially for her. She gets very tired and he's worried about her. She's overworking. She's a workaholic. She's doing it all on her own. He's trying to say to her, “Look, you need to just step away and get help here.” But she doesn't want to do that, of course.

Is that a constant concern for Jack?

Yes. He’s always worried about her in that respect. That has always been her thing – that she's been workaholic and has never had much time for a private life. He's been a bit that way himself, but I think he's finding the balance better now. But she still struggles with that. And so that's always a little bit of a sticking point with them. Jack is always trying to tell Nikki, “Just take some time because this work really affects you.” Think about doing that job for real. I just can't imagine how stressful it would be.

Why does your on-screen partnership with Emilia work so well?

Getting to work with another actor in the same part for 10 years just doesn’t happen very often in this business. It's wonderful. Yes, it's easier in a lot of ways, but at the same time, you have got to keep it alive. Because if you're complacent and you let it go, then you think it doesn’t matter anymore and say, “Who cares?” But Emilia and I are not like that. We really care about what we're doing. We care about each other. We care about the characters. And we both really care about what we say. So we're very lucky to have that brilliant working relationship.

What other contribution does Emilia make to Silent Witness?

She’s the one who has kept it going so well for the past 20 years. Nobody works harder than she does. She really is something when it comes to the show. She will always play it down, and say, “No, it's a team effort”, which it is. But there's nobody who knows the show or the scripts better than Emilia. There is nobody who cares more than she does about what goes out there to people and about what the fans think and what they'd like to see from the characters and the stories. It’s very hard to do that for 20 years. But that’s what she’s done, which is incredible.

What can you tell us about the first episode of this season?

We're just chucked straight back into the mix, really. New case, new people. It seems as if a historic serial killer might be back on the scene. The original cop, who had personal dealings with him, is very, very convinced that this is obviously the work of the same man. She doesn’t seem to have any room in her head for it being a copycat or somebody else. It has to be him. But Jack and Nikki have to be slightly less biased in their investigation. They just have to try and stick by the facts. That’s tricky for Nikki especially because she's leading the post-mortems. And so there are little flare ups between Nikki and the police officer. The detective is solely focused on the idea that the original killer is back, while Jack and Nikki are trying to float some different ideas.

How does it unfold from there?

We meet another pathologist, played by John Hannah, who was not only was the pathologist on the original case, but he also has a personal involvement in that his partner was abducted by this killer and has been missing ever since. But due to lack of money and investigation time, the police haven't been able to do a thorough search. And so he's very cross with the detective, claiming that she hasn't been doing her job properly. So there’s lots going on. It was wonderful to have John Hannah on set. What a coup! He's such a brilliant actor. He is lovely to watch. He's so gentle and thoughtful and quietly strong. He was just a perfect choice for this character. I mean, it's amazing that he did it. We're very lucky to have these superb guest actors.

Cara is now working as an intern at the Lyell. How does her relationship with Jack progress this year?

It's hard because he’s like her dad, but he's not. And so it's a constant push-pull of Jack wanting to help Clara and wanting to encourage her in what she does because she has signs of great talent. But at the same time, he’s trying to protect her because she's still quite young and quite vulnerable, a little bit naive, and hasn't spent much time out in the big bad world yet. So Jack just wants to try and shield Cara a little bit. But it's such a tricky thing with parents. You want your kids to be shielded a little bit, but at the same time they have to go out and bump up against the world. So you can't wrap them up in cotton wool too much. That’s not going to do them any favours.

There is a big development in the relationship between Jack and Gabriel in this series as well, isn’t there?

Yes. Jack and Gabriel have a little bit of a bonding session. Gabriel wants to box. He wants to feel something because he's tired of being in his head all the time. He wants to feel something. So he thinks training as a boxer, then actually having a fight in the ring is an excellent idea. But Jack, who is still a cage fighter himself, is not so keen on this plan.

Does that cause conflict between Jack and Gabriel?

No. If anything, it brings them closer together because thus far they haven't really gelled. I wouldn't have said they were really friends or had spent any time at all particularly together. So at first Jack is reluctant to train Gabriel because he thinks, “This guy? Really?” At then he does it and ends up quite enjoying it. Jack gets something out of it for himself as well as focusing on Gabriel. I think he sees a new side to the guy and that he's got something in him. He's got a bit of steel in him that he likes and that he hadn't seen before. Jack sees that Gabriel is very brave to be doing this. And so cue a Rocky montage all the way!