Set in the fictional Welsh town of Morfa Halen, the crime thriller will follow former detective turned teacher, Jackie Ellis (Kelly Reilly), who after a storm is devastated to discover the body of her eight-year-old student, Cefin, who seemingly drowned. Sending shockwaves through the town, the tragedy takes a toll on the local community, who just three years before were confronted with the sudden disappearance of Jackie’s niece, Nessa – a case which remains unsolved.

“Cefin’s death summons Jackie’s former partner, Detective Eric Bull, back to Morfa Halen to lead the investigation into a community he failed once before,” teases the synopsis. “Convinced the cases are linked, Jackie and Bull must reconcile and race to uncover long-buried secrets inside Morfa, before the storm breaks and all the evidence is gone for good.”

Details surrounding the cast remain scarce, however, Claire Oakley, famed for her work on the 2019 feature film Makeup and the heist series Culprits (2023) is billed as lead writer, director and showrunner.

Speaking about the project, Claire said: “Under Salt Marsh is a crime thriller set in a community deeply connected to its environment, and interwoven with the heartache, fears, dreams and secrets of its people.

“At the heart of it all is Jackie, a character who embodies the wildness of the place we’re depicting. She’s free-spirited, compassionate, and determined, with a steely resolve that makes her truly of the land. We’re absolutely thrilled to have Kelly Reilly bringing Jackie to life.”

For Kelly, the project will mark one of her first since wrapping Yellowstone. Back in June, the A-lister revealed her hopes for Beth Dutton in season five. Speaking to TV Line, Kelly, 47, explained that she’d love to see the character get a happy ending.

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“I mean, I know the ending of the show, which I’ve known for six years,” she told the publication. “We all knew what the ending would be. We’re going to film that this summer.”