What else has Ian McElhinney been in? The Northern Irish actor is known for his roles as Barristan Selmy in Game of Thrones, Morgan Monroe in The Fall, Granda Joe in Derry Girls, General Dodonna in Rogue One, Val-El in Krypton, and most recently as Father Timothy in Mrs Wilson. He has more than 120 screen credits to his name.

Amanda Root plays Olivia Walsh

Who is Olivia Walsh? Pat's wife. A loving mother and grandmother, she is clearly upset about something – but when her son Les discovers her crying in the kitchen, she won't tell him what's wrong.

What else has Amanda Root been in? Back in 1995 she starred in a BBC adaptation of Jane Austen's Persuasion. Since then, she's played Carol Finch in the cold case crime drama Unforgotten, Miranda in All About Me, and Maggie Robinson in The Robinsons. Amanda Root is also known as a stage actress.

Josef Davies plays Les Walsh

Who is Les Walsh? Pat and Olivia's son. He is a loving family man who is devoted to his wife and kids, and has a great relationship with his parents.

What else has Josef Davies been in? He starred in the critically-acclaimed play Hangmen, alongside David Morrissey, Johnny Flynn and Craig Parkinson, and has also been seen on screen in Call the Midwife (as a newborn baby's dad) and The Bisexual (as Evan).

Ray Fearon plays DI Jasper Quint

Who is DI Jasper Quint? A dedicated police officer who works closely with the Lyell Centre on this case. He'll do whatever it takes to get to the truth.

What else has Ray Fearon been in? The actor made a name for himself playing Nathan Cooper in Coronation Street. More recently, he has appeared as Carlo de' Medici in Da Vinci's Demons, Père Robert in Beauty and the Beast, and Carlton Scott in Midsomer Murders.

Emily Taaffe plays Orla Flanagan

Who is Orla Flanagan? An Irish journalist, and an old friend of Jack's. She previously investigated a shadowy organisation called The Guild.

What else has Emily Taaffe been in? Aside from her theatre work, Emily Taaffe has recently had a string of on-screen credits including Megan Morten in Informer, Laurence in the TV series Paula, and Katya in War & Peace.

Richard Durden plays Jack's dad Conor Hodgson

Who is Conor Hodgson? Jack's dad Conor is a man of few words. Father and son are not used to expressing their affection for each other, but they have a close bond. Mr Hodgson is a widower living in London.

What else has Richard Durden been in? Most recently, he starred alongside Benedict Cumberbatch in Brexit: The Uncivil War, playing Bill Cash – his second time pairing up with the actor, after he played his father in TV movie The Child in Time. His other credits include Harlots, Brussel, Agatha Raisin, and Dickensian.

Silas Carson plays Alex Harris

Who is Alex Harris? Olivia Walsh got to know Alex Harris shortly before her death.

What else has Silas Carson been in? Star Wars fans will know him from his role as Jedi Master Ki-Adi-Mundi and Viceroy Nute Gunray in all three of the Star Wars prequels, while Doctor Who fans may recognise him as the voice of the Ood. Silas Carson recently played Khan in the TV series Trust, Haroon Zaman in EastEnders, Marcus Archer in Unforgotten, and Vikram Jawanda in The Casual Vacancy.

Gary Lilburn plays William McDonagh

Who is William McDonagh? An old associate of Pat Walsh. He now lives in a shabby flat in London with his Staffordshire Terrier.

What else has Gary Lilburn been in? The actor played Des in Catastrophe, and Father Quinn in Mrs Brown's Boys.

Des McAleer plays Ken Lawson

Who is Ken Lawson? Ken and his daughter Geraldine run a successful company in England and Northern Ireland.

What else has Des McAleer been in? Pictured here in 2003, Des McAleer has appeared in films and TV shows including My Mother and Other Strangers, The Children Act, and The Crown (as Philip Kinghorn Burbidge). He's actually made two previous appearances in Silent Witness, in 2015 (as a character called Sean Patrick) and 2004 (as George Nevin).

Simone Kirby plays Geraldine Lawson

Who is Geraldine Lawson? Ken's daughter Geraldine has gone into the family business. She's forthright and unapologetic.

What else has Simone Kirby been in? You may remember her as Oonagh from Jimmy's Hall, Irene O'Donnell from Peaky Blinders or Annette Raine from Clean Break. She is also set to appear in the upcoming movie Artemis Fowl, playing Mrs Byrne.

Sean Campion plays Craig Greenwood

Who is Craig Greenwood? The Lawsons' chauffeur. He has known them for decades.

What else has Sean Campion been in? The Irish actor played Virginio Orsini in the historical TV drama Borgia, and Colin Regan in Mr Selfridge. On stage, he was nominated for a Best Actor Olivier Award for his starring role in Stones in His Pockets.

Kiran Sonia Sawar plays Alice

Who is Alice? Alice can be spotted working with the team at the Lyell Centre.

What else has Kiran Sonia Sawar been in? Her TV roles include Ani Shirani in Next of Kin, Shazia Akhand in Black Mirror, and Shereen in upcoming Channel 4 drama Pure.

Lucinda Dryzek plays Marie Walsh

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Who is Marie Walsh? Wife of Les Walsh and mother of two kids – a boy and a girl. The family's life is thrown into chaos when tragedy strikes.

What else has Lucinda Dryzek been in? She actually previously worked with her Silent Witness co-star Amanda Root on the TV series Unforgotten, playing Claire Finch. Other credits include Jasmine Burrows in Holby City and roles in White Gold, Cardinal Burns, and Life of Riley.