‘Still Waters’ Adds ‘Outlander’s’ Mark Lewis Jones, ‘The Crown’s’ Nia Roberts as Production Starts on Second Season of Anthology Thriller (EXCLUSIVE)

Mark Lewis Jones (“Outlander,” “Chernobyl”) and Nia Roberts (“Hidden,” “The Crown”) have joined the cast of upcoming S4C/Sundance Now anthology series “Still Waters” (“Y Golau:Dŵr” in Welsh).

It is the second instalment of the Welsh psychological thriller, which starred Sian Reese-Williams, following “The Light In The Hall” (“Y Golau”).

Reese-Williams (“Wolf”) returns for the second chapter of the six-episode season, which will be filmed in both English and Welsh. She will also be joined by Robert Glenister (“Spooks”), Tom Rhys Harries (“White Lines”) and Maeve Courtier-Lilley (“The Red King”).

Written and created by Regina Moriarty (“Murdered By My Boyfriend”), the new season picks up two years after the first, with Caryl Huws (Reese-Williams) still living in Llanemlyn. But she’s decided to start a new life, retraining as a journalist.

Her first story is one that immediately leads her into a mystery. Fascinated with the newly announced expansion of the local reservoir, she stumbles across an old case, in which a young man was killed at an explosion of the site some three decades earlier. At first it seemed he’d died while committing a terrorist act to protest the expansion, before suspicion turned to his cousin and co-conspirator Rhys Owen (Lewis Jones). Despite Owen’s protestations, he was sentenced to 22 years in prison, where he’s remained ever since.

Huws realizes it’s the perfect story to land her a dream job at the local paper – and hopefully uncover the truth.

Rhys Carter, Erin Richards and Sion Ifan direct the series, which is now in production. It is set to be broadcast next year on S4C in Wales, Sundance Now in North America, Australia and New Zealand and Channel 4 in the U.K. APC Studios is handling worldwide sales.

Long Story TV, Triongl and APC Studios are producing the show made in association with Channel 4 and with the support of Welsh Government through Creative Wales.

Executive producers are Donna Wiffen, Paul Marquess and Jo Roderick for Long Story TV, Gethin Scourfield, Nora Ostler and Alec Spiteri for Triongl and Laurent Boissel for APC Studios along with Gwenllian Gravelle, head of film and dama at S4C and Shannon Cooper, VP for programming at Sundance Now.

“We are incredibly excited to be working again with the talented teams at Long Story TV and Triongl to turn the success of ‘The Light in the Hall’ into an anthology,” said Boissel. “As a producer, we are thrilled to continue expanding the world of Llanemlyn, and as a distributor, we are looking forward to taking the show to further territories around the world.”