Shetland season 8 episode 3 is nothing short of chilling, and as Calder and Tosh's investigation into what happened to Ellen Quinn ramps up, the twists and turns just keep on coming.
The episode opens as we see a strange hooded figure dancing and chanting while pouring petrol onto the grass in a field in the dark. But just to make things even more bizarre, just as the opening credits roll, we see the petrol set alight and that the fire is in the shape of the mysterious symbol from Ellen's tattoo and the dead sheep.
It quickly transpires that Calder hasn't gone home to London as she promised in episode 2, and has instead stayed behind to investigate the mysterious cigarette butt from her sister-in-law, Amma. But before she can get far into her digging, she and Tosh are called to the site where Ellen's body was found and they find a strange corn doll that has been left.
Soon everyone on the police team is searching what the mysterious symbol might be, while Ellen's family comes to the mortuary to identify her body. They confirm the body is Ellen, but while they don't know what the tattoo means when Tosh asks, they do know what the corn doll means, telling the police that Jane Knox makes them, and it could be linked to her.
Ellen's mum, Stella, tells Tosh and Calder that there was bad blood between her parents and the Knox family after they fought over the sale of some farmland. Calder and Tosh head to see Jane Knox, only to find she is dying in hospital and only her son, Tom, is there. They are suspicious of Tom as he is acting strangely and claims not to know Ellen well, only for them to find a book about symbols like Ellen's tattoo, which he claims was his father's.
As the police continue digging, they discover that Ellen made a call from a payphone just before she died. It soon transpires that she was calling Azir Sandat a doctor at Lambank House, which is a psychiatric hospital on the island.
Sandy pays the hospital a visit and Azir admits that he knew Ellen as a patient, but he maintains that he has no idea why Ellen would be calling him. As he is chatting to Sandy he gets a call from his daughter's nursery saying that his wife has collected their daughter early and seemed agitated. Earlier in the episode, we saw her having a panic attack when a postman delivered a parcel and later Azir finds her in the car with their daughter at the free terminal, ready to flee Shetland.
As it transpires that Azir is caught up in some drama with Heather and her son, Neil, Grace Bain is confronting Russ at the farm about the fact they are completely broke. Later it seems Russ is lying to his family when he takes a huge bag of cash from his office drawer and tries to get involved in Cal's dodgy drug dealing business.
As Calder goes to the church to find Amma and ask her about the cigarettes, she discovers her sister-in-law worked at Lambank House and knew Ellen while she was a patient there following a breakdown, but before she can get any further into her questioning, her brother arrives and interrupts.
It soon becomes clear that Heather is also involved with Ellen before her death, telling the police that she was the one who took Ellen to Lambank, but while we know there is a connection between Heather, Lambank, Azir and Ellen, we are yet to find out what it is.
Later, we see a mystery figure at the hospital, breaking into the mortuary. Tosh is woken in the middle of the night by a phone call and it is Cora at the hospital saying someone has broken in and stolen Ellen's body.
At first, the police think it is Tom Knox, especially as the doctors tell them that he was at the hospital the night before visiting his mum but vanished between the hours of 8 pm and midnight. However, after bringing him in for questioning he admits he put the corn doll where Ellen's body was dumped, but he didn't kill her or steal her body.
However, the plot thickens when the police spot a familiar car on the hospital CCTV leaving a car park near the mortuary and it turns out to be Peter Ayre whose house is located near where Ellen's body was originally found. When he was questioned earlier he pointed the police in the direction of Cal after claiming he saw his car near the field the night Ellen died - but was he throwing them off the scent?
After discovering that Peter has been arrested before for criminal damage to livestock, the police go to his house, only to find it dark. Soon they find him in the neighbouring field and it turns out he is the mysterious figure setting fire to the storage symbol in the grass from the start of the episode.
As the police get closer, Calder and Tosh wrestle him to the floor before he can set fire to what looks like a bonfire, and they soon realize that Ellen's body is in the middle of it. Thankfully before the ritual can go any further, Peter is arrested.
But that's not the end of the twists for this episode, because as Calder gets back to her hotel, she is confronted by a woman from her past who she has been avoiding. It transpires that this woman had an affair with Calder's father while her mother was dying, and Ruth doesn't want to hear her excuses. However, her blood runs cold when the woman says she wasn't the only one that Calder's father was sleeping with, and that he was also having an affair with Stella Quinn, who was not only half his age, but also the mother of Ellen Quinn.
Could this mean that Ellen and Calder are half-sisters? Has Ruth been investigating her own sister's murder and not even known it?
Shetland season 8 is available on BBC iPlayer in the UK and BritBox, from November 29, in the US.