Under Salt Marsh: Yellowstone’s Kelly Reilly stars in an eerie thriller where everyone has something to hide

It’s one of those unsettling trends that you don’t realise is a thing until someone points it out: the dead child at the beginning of a thriller. But, while Under Salt Marsh leans into this unsettling opener, rest assured that it is far from your average murder mystery. And not just because Yellowstone’s Kelly Reilly (speaking in her natural English accent) is phenomenal as Jackie Ellis, a former detective forced to confront old failures while untangling a new horror in her hometown.

Rather, it’s because this show – in all of its twist-filled, tense and atmospheric glory – quickly proves it’s more about intuition, human fragility and the messy brilliance of women we often overlook.

The plot kicks off when Jackie discovers the body of eight-year-old Cefin in a drainage ditch and quickly draws eerie connections to the cold case that cost her her job as a police detective years earlier. 

When Eric Bull (Rafe Spall), her former police partner, returns to investigate this new crime, the pair are forced into a compelling push-and-pull relationship when they discover there’s something strange about the water in the boy’s lungs.

Which means, yes, there is a far bigger conspiracy waiting to be exposed. 

What makes Under Salt Marsh feel fresh isn’t just the mystery; rather, it’s Jackie. She’s messy, fallible, irritable and endlessly human, with the kind of instantly iconic coat that Marcella would kill for yet still somehow locks in on all the clues and conspiracies that the men around her can’t seem to see. Honestly, watching her navigate old demons, a new murder and a storm threatening to wash the entire bloody town away is the perfect reminder that imperfect women often get shit done, even as people talk over us and tell us to stop being so emotional.

Of course, one of the people talking over her (at least for the first episode) is Detective Bull. Jackie trusted him, once upon a time. He betrayed her. And now here he is, back in Morfa Halen, and watching them clash is – not to get too Benoit Blanc about it all – damned compelling. 

Enemies-to-lovers? Maybe. Enemies-to-grudging-allies in a terrible, storm-lashed situation? Definitely. The tension crackles in every scene, whether they’re bickering over evidence, undermining one another or slowly realising that, despite themselves, they need each other to solve the case. It’s messy, combustible and oddly satisfying – exactly the kind of dynamic that keeps you glued to the screen. 

Meanwhile, the Welsh landscape is as much a character as anyone: windswept, eerie and stunningly beautiful, adding weight to every scene. There are child gangs to contend with in addition to all the hidden secrets and lies that layer through the town like sediment in the marsh. Amid it all, Jackie’s intuition shines. Dialogue is sharp and quotable: “You’ve got to listen to your doubts. And if you don’t have them, you’ve got to find them” and “Evidence has already been washed away. We don’t have time for fucking rules.” Two episodes in, and I’m already hooked.

Perhaps the most intriguing creative decision is the looming once-in-a-generation storm. In the wrong hands, it could have felt like a gimmick, a ticking doomsday clock. Here, though, it’s quietly terrifying, a subtle but constant reminder of how climate change shapes our lives. Floodwaters hide secrets, encroaching tides mirror human fragility, and a shocking shot of a landfill late in episode two underscores the destructive impact of humans – not just on each other, but on the world around them.

Throw in powerhouse performances from Jonathan Pryce, Naomi Yang, Harry Lawtey and Rhodri Meilir, and you have more than enough reasons to tune in to this story of women’s intuition, flawed brilliance and environmental neglect.

All of which brings me to this: if you’re missing the heady suspense of Broadchurch, or just love watching a flawed woman quietly dismantle the patriarchy while solving a mystery, this is one to binge. Enjoy.

Watch Under Salt Marsh on Sky and Now on 30 January, Sky and Now 

Images: Sky