“She’s with a mate. Nothing’s going to happen to her.”

Many a parent consoles themselves with that thought while waiting for their almost grown up teenager to come home in the gloomy dark. For most of us we’re right but sometimes – just sometimes – the dread is portentous.

For Detective Inspector Perez, the dread was not for his own daughter who was out carousing but for Katherine Ross whose body was being pecked by birds on the beach. Earlier we’d seen her swigging from a bottle and dropping by with her friend to visit an older man named Bain, played by Brian Cox, who lived at the top of the hill with his pet raven. Bain talked about having difficulty sleeping in the summer dim and having seen her dead at five in the morning when he went out to investigate why there were so many birds on the beach. Sally Henry, the teacher’s girl, was her friend and being portrayed as the innocent girl led astray by flighty Katherine who had only come to the island a year ago after her mother died. Sally did look like a rabbit caught in the headlights but she said that Katherine had called on Sally in the late afternoon and also drip fed details of Katherine the rebel who thought respect was something that had to be earned and that some adults were ridiculous.

There was the possibility of a link between Katherine’s death and the disappearance years before of a little girl called Catriona who had lived at the same address as Katherine. Facebook, even on Shetland, made Perez’s job more difficult as rumour took hold. Freaks and monsters might take over the imagination and force out the truth. She had been strangled between 12 and 4 in the same area that her body had been found and there were no defensive wounds on her hands, although the skin under her nails was probably her own. The footprints on the beach were her own. The school allowed Perez to talk to her classmates to plead for information. Her media teacher Hugo Scott  thought she was a bit too spiky to be properly popular with her classmates. Katherine stood out because she refused to use social media.

The real star of the show remains Shetland, particularly Lerwick with all its nooks and crannies even although we are sometimes watching it on CCTV to narrow down the time of death.