Based on a real-life story, Jeff Pope's new ITV drama A Confession introduces us to Detective Superintendent Steve Fulcher (Martin Freeman) and his mission to catch a killer after the disappearance of 22-year-old Sian O'Callaghan in 2011.
Here are the cast and characters you need to meet...
Martin Freeman plays Steve Fulcher
Who is Steve Fulcher? Detective Superintendent Steve Fulcher of Wiltshire Police is preparing for a quiet Saturday at home when a call comes in: a local young woman, Sian, has failed to return home from a night out. He immediately devotes himself to the case, determined to find Sian – whatever it takes.
What else has Martin Freeman been in? Martin Freeman stars alongside Benedict Cumberbatch in the TV series Sherlock, playing the famous Dr John Watson. He was Bilbo in The Hobbit trilogy, and recently played Everett K Ross in Black Panther.
Imelda Staunton plays Karen Edwards
Who is Karen Edwards? Watching the Sian O'Callaghan case unfold, Karen feels huge sympathy for the family. Her own daughter Becky has been missing for over eight years – disappearing after a long, difficult battle with drug addiction.
What else has Imelda Staunton been in? Harry Potter fans will know Imelda Staunton as evil headmistress Dolores Umbridge. She was nominated for an Oscar for her role in Vera Drake, and has won four Olivier Awards for her theatre performances. Other credits include My Family and Other Animals, Cranford, The Girl, and Pride.
Fun fact: she is married to Jim Carter (aka Mr Carson) – who co-starred alongside Siobhan Finneran in Downton Abbey.
Siobhan Finneran plays Elaine Pickford
Who is Elaine Pickford? Sian's mum. Although at first she insists that Sian must be sleeping off a hangover at a friend's house, she quickly becomes terrified about what may have happened to her daughter.
What else has Siobhan Finneran been in? The actress starred as Mrs O'Brien in Downton Abbey. She has recently played Nikki Kirkbright in Cold Feet, Becka Savage in Doctor Who episode The Witchfinders, and Sally Newell in The Widow. Siobhan Finneran is also known for playing Clare Cartwright in Happy Valley, and Janice Garvey in Benidorm.
Joe Absolom plays Christopher Halliwell
Who is Christopher Halliwell? A local taxi driver.
What else has Joe Absolom been in? Long-time Doc Martin star Joe Absolom plays the character Al Large. He has also appeared in The Level (as Shay Nash) and in EastEnders (as Matthew).
Charlie Cooper plays Kevin Reape
Who is Kevin Reape? Sian's boyfriend, who raises the alarm when Sian fails to return home from her night out.
What else has Charlie Cooper been in? Charlie Cooper co-writes and co-stars in the comedy series This Country, playing Lee "Kurtan" Mucklowe. This is his first role in a serious TV drama.
Peter Wight plays Charlie
Who is Charlie? Karen Edwards' husband. For years he has been helping her search for Becky, but so far it has been fruitless.
What else has Peter Wight been in? With more than 140 acting credits to his name, Peter Wight has appeared in everything from The Crown (as a newspaper editor) to Vanity Fair (as Mr Raggles) to Hot Fuzz (as Roy Porter).
Faye McKeever plays Deborah Peach
Who is Deborah Peach? Fulcher's colleague at Wiltshire police.
What else has Faye McKeever been in? The actress starred as Linda in the TV series Trollied. She played Claire Olssen in Little Boy Blue, and Petra Jamieson in The Moorside.
Ian Puleston-Davies plays Mick O'Callaghan
Who is Mick O'Callaghan? Sian's father. He and Elaine split up some years ago.
What else has Ian Puleston-Davies been in? Recently, you may have seen him in Pennyworth, Hatton Garden, or Tin Star. He also played Peter Cullen in Marcella and had a five-year stint as Owen Armstrong in Coronation Street.
Christopher Fulford plays John Godden
Who is John Godden? Becky's father. He and Karen separated many years ago, and after Becky disappeared he continued telling Karen that his family members had seen her alive.
What else has Christopher Fulford been in? The actor has appeared in a bunch of TV shows and movies, usually in smaller roles. He played DI Brian Marjoram in Manhunt, and has also recently appeared in Burning Men, Dark Heart, Grantchester, and Queen of the Desert.
Stephanie Hyam plays Becky Godden-Edwards
Who is Becky Godden-Edwards? Karen's daughter. She has been missing for eight years, and Karen still hopes she will decide to come home.
What else has Stephanie Hyam been in? Stephanie Hyam made a memorable appearance in Bodyguard, playing Julia Montague's posh Personal Assistant Chanel Dyson. She played Michael's girlfriend Charlotte Murray in Peaky Blinders, was Anne Lister's travelling companion Sophie in Gentleman Jack, and played Heather (aka 'the puddle girl') in two episodes of Doctor Who.
Florence Howard plays Sian O'Callaghan
Who is Sian O'Callaghan? A young woman who goes missing from Swindon Old Town in 2011.
What else has Florence Howard been in? Other than the role of Gabby in an episode of Dead Pixels, this is her first on-screen role.
Gary Oliver plays DCC Pat Geenty
Who is DCC Pat Geenty? Detective Chief Constable Pat Geenty is one of Fulcher's bosses at Wiltshire Police.
The real Pat Geenty took early retirement in 2015.
What else has Gary Oliver been in? You may have seen his appearances in Victoria, Benidorm, or Franco – but perhaps his most high-profile appearance has been in Game of Thrones, where he played Ternesio Terys.
David Keeling plays CC Brian Moore
Who is CC Brian Moore? Chief Constable Brian Moore is another of Fulcher's superiors in the police force.
What else has David Keeling been in? The actor has previously played policemen (of various sorts) in the TV shows Strangers, Prisoners Wives, and Murdered by My Boyfriend.
David Nellist plays DI Steve Kirby
Who is DI Steve Kirby? One of Fulcher's colleagues.
What else has David Nellist been in? In the TV series Sherlock, he played Mike Stamford. Further credits include Taboo, Much Ado About Nothing, and 55 Degrees North.
Jessica D'Arcy plays Lora O'Callaghan
Who is Lora? Sian O'Callaghan's little sister.
What else has Jessica D'Arcy been in? Young actress Jessica D'Arcy has previously appeared in Urban Myths (as Kate Dickens) and Electric Dreams episode Human Is (as Agent Dov).
Kate Ashfield plays Yvonne Fulcher
Who is Yvonne Fulcher? DI Steve Fulcher's wife.
What else has Kate Ashfield been in? The actress is currently starring in Sunday night ITV drama Sanditon – playing Mary Parker, the supportive but worried wife of Kris Marshall's Mr Tom Parker. That's just one in a line of 'concerned TV wives' she's played, as she also starred as Jools Gates in the first season of Line of Duty (opposite Lennie James as husband DCI Tony Gates). Other credits include Shaun of the Dead, This Little Life, Secrets and Lies, Collision, and The Diary of Anne Frank.
Derek Riddell plays Pete Shawe
Who is Pete Shawe? Elaine's boyfriend – a pilot.
What else has Derek Riddell been in? Recently, you may have seen him in Shetland (as Chris Brooks), Gentleman Jack (as Captain Sutherland), or Fantastic Beasts: The Crimes of Grindelwald (as Torquil Travers). Other credits include Action Team, Hard Sun, Gunpowder, W1A, Mary Shelley, The Missing, and Happy Valley (as Richard Cawood).
Jake Davies plays Liam O'Callaghan
Who is Liam O'Callaghan? Sian's brother. When he finds out from Sian's boyfriend Kevin that she failed to return home on Friday night, he calls his mum in a panic.
What else has Jake Davies been in? The actor has made appearances in Black Mirror, Ghost Stories, Silent Witness, and Cyberbully. He was Matthew Webster in TV series The Missing.
Maimie McCoy plays DC Tracy Joyce
Who is DC Tracy Joyce? Fulcher's colleague at Wiltshire police.
What else has Maimie McCoy been in? The actress played Nicole in Personal Affairs, Tamsin Richards in DCI Banks, and Milady in The Musketeers.
Dominic Tighe plays DS Bob Cooper
Who is DS Bob Cooper? Fulcher's colleague at Wiltshire police.
What else has Dominic Tighe been in? He was in the TV series Next of Kin as Richard Payne, and played Clive Howard in an episode of Call the Midwife.
Caroline Bartleet plays DS Sarah Bilson
Who is DS Sarah Bilson? Fulcher's colleague at Wiltshire police.
What else has Caroline Bartleet been in? Caroline Bartleet's screen credits include Murdered by My Boyfriend (where she also played a policewoman) and The Eichmann Show (also starring Martin Freeman). In 2015 she wrote, directed and produced a short film called Operator, starring Vicky McClure and Kate Dickie, which won a BAFTA.
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Jason Milligan plays DS Eddie Strange
Who is DS Eddie Strange? Fulcher's colleague at Wiltshire police.
What else has Jason Milligan been in? Credits include TV series Strangers, The Afternoon Play, and The Emperor's Wife.