The fictional TV series is set to the backdrop of the stunning Scottish isles, but shows the dark side of one of the most beautiful places on earth.
Leading the cast is Douglass Henshall as returning detective inspector Jimmy Perez - alongside some other returning faces and a few new cast members.
So, what is series six about and who stars in the BBC One drama? This is what you need to know.
What is Shetland series six about?
The BBC teased season six as a six-part series where a murder investigation on the island takes a “dark and sinister twist”.
DI Perez and his team investigate the death of a prominent local figure, but the case leads Henshall down a path which will uncover lies and secrets from the past.
The local figure also played a singing role in the release and return of murderer Donna Killick, who was sentenced for the historic murder of teenager Lizzie Kilmuir.
Convict Donna is released from prison after being diagnosed with cancer and she returns to Shetland, which many feel is poor judgement and leaves the grieving community shocked and angered.
Perez is also dealing with the death of his own mother, so struggles to come to terms with her loss while taking on the case and the grieving family left behind.
Alison O’Donnell, who plays Perez’s partner Tosh, also referred to the upcoming series as “Shetland-centric,” focusing more on the local people and area and the culture of the island.
Who is in the cast?
Douglas Henshall as DI Jimmy Perez
In the lead role is Douglas Henshall (In Plain Sight; Primevil) as DI Jimmy Perez, the lead investigator who has featured as the main character since the show’s inception in 2013.
Henshall said of returning to the series three years on from season five: “Perez is just in my bones now. Normally it takes me around a week to start to feel comfortable playing him again but after that it’s pretty straightforward.”
Alison O’Donnell as Tosh
Alison O’Donnell plays DS Alison ‘Tosh’ McIntosh, the supporting investigator who works closely with Perez and was promoted in the last series. She has also found love since the show began, forming a relationship with Donnie (Angus Miller).
O’Donnell joked about the time between series, telling the BBC: “A second baby and a global pandemic between Seasons five and six so, for me, suffice to say I had been on a bit of a journey personally.
However, she’s glad to be back, “returning to Tosh was an absolute tonic,” she added.
Steven Robertson as Sandy
Scottish actor Steven Robertson returns as Sandy, who was forced to retrain after being suspended from his role as a detective. In series six, he struggles with the return of Donna as she was convicted for the murder of his childhood friend.
Robertson’s character faces internal conflict in this series, as he tries to prove himself as a detective while battling his frustrations that Donna has returned.
He told the BBC: “Sandy’s one of those people whose strengths and weaknesses are, like many of us, ultimately the same thing. He absolutely always wants to do the right thing by the islands and to see what is wrong put right and what he sees as right protected at all costs. It’s not completely black and white, binary thinking but he does have a very strong sense of what’s right and wrong.
“This can be hugely useful in the investigations but perhaps he needs to learn to also give a little more of the benefit of the doubt.”
Mark Bonnar as Duncan
Guilt star Mark Bonnar also returns, as Donna’s former lover and Perez’s friend, Duncan. Bonnar described his character as “a bit like me, a bit hapless, a bit try-hard and a bit grumpy.”
Duncan is the unlikely partner of Perez, but the two have a great relationship and both actors have alluded to their onscreen partnership.
Bonnar said: “Duncan and Perez are very different people but we have a lot of respect for each other even though Duncan’s ultimately very annoying and get himself into scrapes that are always avoidable.
“I think Perez looks on Duncan with an eye roll and a sigh. It’s like long-suffering Perez and well-meaning Duncan. Perez describes it perfectly at the end of series five - being pals with Duncan is like supporting the Scotland football team... you always hope they’re going to get there in the end!”
Neve McIntosh as Kate Kilmuir
Neve McIntosh (Bodies; Marple; several Doctor Who episodes) stars as Kate Kilmuir, she first joined Shetland in series four when her character’s sister was the victim of a murder. In series six, her character is explored further as she is shook by the return of her twin sister’s killer, Donna.
Asked about the strength of her character, she said: “One of Kate’s strengths is to keep going; to not give up but her weakness is not stopping when it’s over. She hasn’t paused to take stock so her thinking isn’t clear.”
Stephen McCole as Logan Creggan
Also joining the cast is Stephen McCole (Orphans; High Tide)as ex-serviceman and Shetland resident Logan Creggan. He plays the role of a man haunted by his past, having served in the army. His initial involvement in the case focuses on his son Fraser (Lewis Gribben), but it soon becomes apparent he has links to the murder victim too.
McCole was very complimentary of the island itself, referring to Shetland as “gorgeous” and “one of the best locations I've had the pleasure of spending time in.”
He added: “I have to say though, it’s a fine collection of folk in that crew and it was a pleasure spending every day with them.”
Erin Armstrong as Cassie
DI Perez’s step-daughter Cassie also returns, played by Erin Armstrong (World’s End; Glasgow Girls). Cassie has left the island to study at university in Glasgow.
Julie Graham as Rhona Kelly
The Bletchley Circle’s Julie Graham returns as prosecutor Rhona Kelly. She works closely with Perez and has been in the show since 2014.
Lewis Howden as Sgt Billy McCabe
Sergeant Billy McCabe also returns, played by Lewis Howden. Though he is primarily a stage actor, he has also featured in Aberdeen (2000) and Monarch of the Glen.
Others joining the cast include Anne Kidd (One of Us) as forensic scientist Cora McLean, as well as Angus Miller as Donnie and Anneika Rose (Ackley Bridge, Line of Duty) as Maggie Keane
Where can I watch Shetland on BBC?
Shetland returned to BBC One on Wednesday 20 October at 9pm and airs across six consecutive weeks, concluding on 24 November.
All episodes will be available on BBC iPlayer, shortly after being shown on BBC One.