Debuting to rave reviews and strong viewership numbers, Blue Lights has quickly become a great example of how the classic police procedural can still feel vital and true to the modern day. Set at the Blackthorn police station in Belfast, Blue Lights follows three new police officers as they contend with the brewing conflicts and lingering feuds bubbling just under the surface of the city.

Season 4 is directly building off the tensions from season 3, with conspiracies involving MI5 and conflicts that spiral out of a riot that broke out in the season premiere. Ahead of the season’s American debut on BritBox, TVBrittanyF got the chance to speak with Blue Lights co-creator Declan Lawn and star Siân Brooke about the biggest surprises of the season — and mused on the future of the property.

TVBrittanyF: Coming into this series, you already had the previous three years to build on. What were the vibes coming into this new batch of episodes?

Declan Lawn: I was excited. I mean, those first few minutes, there’s quite a lot of violence. I think it’s our biggest set piece sequence that we’ve ever done on the show. We decided to hit the ground running and try and shock the audience because usually we start kind of quiet. This year we said, ‘Let’s go big or go home.’ I’m really proud of it. This is my favorite season of the four, and partly that’s because I think episode one just really lights a fire immediately, and it never goes out.

Siân, you’ve gotten some real time with Grace over the course of the show. What was it like this year to see so much of that growth come to fruition?

Siân Brooke: I think [this series] shows her as fallible. I think there’s a certain young girl that gets under her skin. I feel like Grace has always had a great capacity for forgiveness and understanding and patience. I think with this young girl, she finds that really hard. It shows her as a normal person like everybody else. There are certain things that this girl does; I think Grace really prides herself on putting herself out into the world as quite a strong, moralistic person, essentially a good person.

Then this young girl sort of shows how she can be perceived as something very different, and I think Grace doesn’t like that. I think we also see that ego that Grace sort of has, which I think is a wonderful thing to have with a character that’s always been so graceful. There are times within this series that she lacks that. I think these are a couple of volatile moments, or, as I would say, angry shouting [Laughter].

What would you both say surprised you the most in this series?

Declan: So there are so many things because I’m constantly surprised when I watch it. It’s just not like how I imagined it in my head, and it’s nearly always better and more emotional. When you’re writing the script, you’re kind of doing your job, and you’re imagining how things might be. But I was so surprised in episode four when I first watched it, the Jerry episode.

There were times when I got very emotional, and the last scene of the entire series, one of the final shots, is Grace looking at herself in the mirror, reflecting back over the last four years. I got very emotional at that point as well. It’s a weird thing. Even as a writer, the actors are bringing something to it, and the directors’ and the set designers’ hats make it fresh for me as well. It’s a very strange thing. It’s constantly surprises me, constantly.

Siân: I think with series, what was lovely is that we were paired up with different characters as well. Grace gets to hang out quite a lot with Annie in terms of investigations, and that is the beauty of the show. They have written these wonderful characters that operate individually, but then you can put them in these different pairings, and it actually adds another taste to the show.

I got to hang out with Katherine, who plays Annie, and that was just lovely because it was another dynamic to explore. Then, with Michael Smiley, who plays Colly, it was a totally different energy. That really surprised me because your character behaves in a different way around different people. It surprised me, and I hope it surprises other people.

Declan, you’ve been somewhat cagey about whether or not you’ll return for another series. Do you have ideas of what you would like to see for Blue Lights down the line?

Declan: There’s a very strong sense of an ending in season four, and that’s because the BBC commissioned seasons three and four together. We planned that story as a 12-episode arc. Now, it feels like it has a massive sense of closure. You get the sense that a lot of the characters have completed their journeys, and everything is changing around them. So partly that’s true because for me, as a writer and with my co-writer Adam, we are moving on.

I just feel like my story’s been told. My shift is over. I kind of said everything I want to say. I think there’s probably more gas in the tank for the show and the brand, with spin-offs following some of the characters or going to new places and new stations. It would be great if that happens. But for me, I realized over a year ago that we could say everything we wanted to say in four seasons. I just like the idea of going out on a high. It’s an end for me on the show, but hopefully, not an end for the show.

Blue Lights series 4 premieres November 12 on BritBox