An Outlander actor has undergone a dramatic transformation for a new role in a mystery thriller.

Mark Lewis Jones, the Welsh actor known for his role as Tom Christie in the sixth season of Starz’s historical epic Outlander, is set to star in the upcoming drama Y Golau: Dŵr, also known as The Light in the Hall: Still Waters in English, reports the Daily Record.

The series marks its triumphant return three years after its debut, The Light in the Hall, in 2022.

In the second season of the acclaimed Welsh anthology series, young journalist Caryl Huws, portrayed by Siân Reese-Williams, finds herself embroiled in a complex web of personal betrayal, family secrets, and dark mysteries as she investigates a controversial local reservoir expansion plan.

As Caryl delves deeper, long-buried tensions resurface, and questions arise about the imprisonment of Rhys, played by Jones, for the murder of his cousin during protests against the expansion three decades ago.

Joining Jones and Reese-Williams in The Light in the Hall: Still Waters/Y Golau: Dŵr are Steeltown Murders actress Nia Roberts as Eve Davies, and Robert Glenister from The Night Caller and Sherwood as Robert Davies.

Additional cast members feature Netflix’s White Lines star Tom Rhys Harries portraying Hari Breckon, The Red King’s Maeve Courtier-Lilley returning as Mabli Davies Owen, Dal Y Mellt performer Wyn Bowen Harries taking on Bryn Owen, Mali Tudno Jones from Bariau appearing as Megan Breckon, Broadchurch star Matthew Gravelle playing Gareth Breckon, and 35 Awr actress Gillian Elisa stepping into the role of Eunice.

The fresh series will once again unfold in the imaginary Welsh community of Llanemlyn, with creator Regina Moriarty collaborating alongside Siân Naiomi, Anwen Huws, Catherine Linstrum, and Angharad Elen on the screenplays.

The Light in the Hall: Still Waters/Y Golau: Dŵr will initially be broadcast in its home nation of Wales in the Welsh language edition with subtitles this September. The show transmits at a subsequent date across the remainder of the UK on Channel 4.

The debut series garnered favourable critiques from reviewers with viewers expressing their admiration on IMDb.

One individual praised it as “mesmerising” and remarked: “Wow this was good. Joanna Scanlon and Alexander Roach both starred in the brilliant No Offence and are both excellent here too.”

Meanwhile a 10/10 assessment declared: “Once you start watching it you can’t stop, you’re almost holding your breath! Actors are absolutely amazing, spot on!” One viewer enthused: “You will not waste your time watching this, and I always love when they film absolutely beautiful, and I don’t think I’ve ever seen a show with any one of these individual actors in it that I didn’t like, they never let you down, their faces are what draw you in, because you know they’re great actors but they’re acting keeps you watching!”

Another glowing review read: “In a world where popular crime dramas fall into the same predictable formula, it’s refreshing to see something brave enough to do things a bit differently.

“The early episodes start at a slow pace, but there’s a real effort to develop the central characters before it changes gear and becomes a highly engaging (and unpredictable) thriller.

“The decision to set the show in the dramatic Welsh countryside was a triumph and a 6 episode British crime drama with very little police involvement is both refreshing and bold.”

The Light in the Hall: Still Waters/Y Golau: Dŵr will air on S4C on Sunday, September 14 at 9pm and later on Channel 4 and AMC+

Outlander season 8 will air on Starz and MGM+ via Prime Video in early 2026