SPOILER ALERT: This article contains major spoilers for “Under Salt Marsh,” which had its season finale on Friday.
“Under Salt Marsh” is one of Sky Atlantic’s biggest non-HBO drama pushes in recent years. The original six-part series (Sky has yet to confirm where it’ll land in the U.S.) stars “Yellowstone’s” Kelly Reilly as Jackie, a detective turned teacher with an unfinished case that comes back from the dead when, late one night after a secret tryst, she stumbles across the lifeless body of one of her pupils in a ditch. Soon, it’s confirmed that he’s been murdered, making him the second child to die in the small Welsh community of Morfa Halen in three years. With a storm threatening to destroy vital evidence – as well as the coastal village itself — Jackie teams up with her old police partner, Detective Eric Bull (Rafe Spall), to try and find the killer.
Ahead of the season finale on Feb. 27, Claire Oakley, who created, co-wrote and co-directed the series, sat down with Variety to talk about her inspiration for “Under Salt Marsh,” if Mac was always going to be the killer and whether audiences will see Jackie and Bull team up again for a second season.
Where did the idea for the show originate?
I really wanted to set something [in North Wales], because I’d really fallen in love with the area, and particularly the salt marshes. They’re such a rare and unique environment.
And I came up with the idea that if we had a detective series, then we could get really into the fine detail of these marshes, and suddenly the ecology and the salt content in the water and all of these little things would become really vital.
This is a bit conceptual, but the salt marshes protect us. They protect us from the sea level rise from the storms. So they’re very important if we want to continue living here, because our island is getting smaller. And so [there as] this idea of protection and “What if we don’t protect the things that we need to?” What if we don’t protect the future generations against potential horrors? I started to think about the plot in that way, like, how would this detective story, this murder mystery, reflect that idea?
Claire Oakley and Kelly Reilly on the set of “Under Salt Marsh” (Courtesy of Sky Atlantic)
One early scene a lot of viewers have discussed is in Episode 1, when Jackie insists on telling Cefin’s parents about his death rather than letting the police do it. Why did you make that choice?
I liked the idea that Jackie is often acting on instinct and that is probably what made her ultimately leave the police and perhaps not be the best type of person to join the force. In some ways, she’s a very good detective. In other ways […] she can’t cope when things get personal. And I wanted to put her in a position early on where, as a human being, maybe she felt it was right that she had to tell the parents as soon as she could, they were going to be the first people that she would go to and she wasn’t going to wait for the police, who, in this particular community, might take quite a long time to get there. But as it’s happening, [she’s] realizing, like, “oh […] it’s kind of a very irresponsible thing to do.” I was interested in these moments where she’s not responsible, but she’s responsible emotionally, on a human level.
I also really liked in that scene the idea that she turns up covered in mud and shell-shocked and pale and obviously in distress. And their response to her is like, maybe that’s not abnormal [for Jackie]. Like, “We thought you were doing well, Jackie. Sit down and I’ll call your dad.” It was a way to understand that she had a complicated past.
Viewers have also been remarking on Jackie’s big age gap relationship with Dylan (played by Harry Lawtey). Was that written into the script or was it a result of casting Lawtey?
It was written in. I felt that [worked] for Jackie, the idea of a younger boyfriend who might not demand from her all the things that someone her own age might demand — Like, are we going to move in together? What’s going to happen? Is this a real relationship?
She could get love and passion and sex from this person, while also not having to give much of herself and not have to take responsibility in that way.
Was there a particular intention behind making Jackie pregnant?
I liked this idea that she’s stuck in the past. She can’t move on until she finds out what happened to Nessa — a little bit like the whole community, they’re already eroded by this awful thing that has happened — but she, in particular, can’t. On the surface she’s got a new job, she’s got a new career, she’s doing it. But the pregnancy allowed me to suggest that all is not quite well. If you are happy and you feel steady about your future, there’s no reason not to tell your boyfriend that you’re pregnant or really anyone else.
I was actually also pregnant as I was writing it, so that almost certainly gave me some insight.
In Episode 6 where the storm has hit the village and Jackie is chasing after Dylan, there’s a huge wave that hits his car. How did you create that scene?
We built the whole center of the village. The chip shop, the butcher and that whole T-junction, where that wave occurs, is all a set in Dragon Studios in Cardiff. It was all built outside on the back lot of the studios, and we had to create this special concrete pad that had to take the weight of all of the set and also the water.
We had a first level of water. When Jackie and Dylan are there, it’s kind of knee-high. The cars can still drive through it. So that was the first level of water and we were working in that water. It was January. There were like 1,000 conversations about, “What if the water freezes?”
But we couldn’t heat the water because then it starts to steam. Then there were endless conversations about, “How long could someone — either a member of the cast or crew — be stood in this almost freezing water at a time? Were we going to be able to shoot a 6-page dialogue scene?”
And then that wave. We had this huge kind of slide, essentially, with massive buckets of water at the top on cranes, and we tipped them down, and so they shot out across. The car was rigged on a winch. So as the water came, we winched the car backwards, because the water was never going to be powerful enough to move the car in reality.
A lot of what you see was done in camera but then the water was augmented to be slightly bigger — so that we could believe it would push the car — in VFX.
Rafe Spall as Detective Eric Bull in “Under Salt Marsh” (Courtesy of Sky Atlantic)
And what about the scene when Mac has locked Bull in the room, which is flooding with water, until James [Osian Emlyn] stumbles across him and lets him out?
That was actually two different sets. Inside the room, when it’s filling with water, we had a hydraulic set that was a three-sided room on a hydraulic platform that went up and down in a tank in like a big swimming pool. So as it’s filling with water, we’re just slowly lowering the set into the water as Bull does his take.
There was no door in that set. So the opening of the door was in another set that we built where it was the outside of the room, that kind of corridor-y bit and the stairs. And when [James] opened the door, in real life we had a stunt person.
Was Mac always going to be the murderer?
Not really, no. I was commissioned by Little Door to write the pilot, and that was before we took it to Sky.
I hadn’t planned out the whole series. I think I had a brief outline […] and that these were the things I wanted to explore with the killer and it needed to be linked to the environmental reasons why he did it or she did it. But I didn’t have anyone pinpointed. And then Sky came on board and they wanted a second episode written before they decided on whether to greenlight it or not.
We did a small writers’ room. It was me and Jonathan Harbottle, who came on board to write Eps 3 and 5 at that point, and we sketched out just the first half, so the next two episodes, so Eps 2 and 3 together, and then I went away and wrote Ep 2, and we still didn’t know who the killer was. We still hadn’t addressed the second half of the series. And so I wrote Ep 2, had [my] baby, we got greenlit, John wrote Ep 3, and then we realized we had to figure out the second half of the series. And so we did another writers’ room, and that’s when Nikita Lalwani came on board, who wrote Ep 4. We did it in my sister’s house, she lives one street away from me, so that I could be brought the baby to breastfeed every three hours while we were doing the room. And I think we did 8 days and we planned out the second half of the series.
It wasn’t ideal, in a way. In some ways it meant it happened very organically, the story. In other ways, it made things hard, because we’d already had three eps written without really knowing the ending.
You then have to go back to the beginning, and re-work things in and feed things in. Like, we knew with Mac, once we’d settled on him, then it’s about protecting your reveal but when he’s finally revealed, I didn’t want people to say, like, “What the fuck?” I want people to say, “Of course, holy shit, it’s him. How do I not see that?” So it needs to add up and not be too wacky.
When you have a story about two kids being murdered, there’s the possibility it’s sexually motivated. But Nessa and Cefin are both killed – directly or indirectly – because of the toxic waste. Did you ever consider giving Mac a different motivation?
No, I definitely didn’t want to explore a sexually motivated crime, or even a crime of passion or a psychopath or those sorts of things. I was interested in exploring the idea that someone “normal,” if any of us were in that specific situation, we may have done the same thing. That it was just someone who was under a huge amount of pressure, whose idea of life had become skewed because of that. And it was a bit of a self-protection; he ultimately kills those children in order to protect his reputation and his status in the community and what he feels he’s doing for good. He’s building this seawall, he’s protecting this community, but at what cost? “But at what cost are we doing these things?” was the idea that I was trying to dig into. So I wanted the crime and the killer to represent those themes right from the beginning.
Is there a likelihood we’ll see Jackie and Bull reunite for a second season?
We’re exploring what a second season might look like. We’re looking at different options of how we could take it forward, if it got commissioned.
This interview has been edited and condensed for space and clarity.