Warning: contains spoilers (and potentially spoilery speculation).With apologies for my icy heart, I dont give a mussel spat about the Harris family. This weeks flashback opener, which showed Sad John Harris inducting into the family business the wee son hed just brained to death with a grappling hook, left me cold. Not as cold as Ruth, Tosh and the rest of the Shetlanders are, admittedly their every conversation shouted over cassette tape-hiss winds that play merry havoc with loose hair and must require hours of overtime in the dialogue replacement booth each series. This ones set in June, incidentally. Thats a Shetland summertime.My preoccupation with the weather is a bad sign for series nine; it signals that instead of being drawn into the story, my minds wandering. Tosh will be making a house call on the latest suspect to find out what they were doing on the night Annie and Anton were murdered, but instead of hanging on their every word, Im gazing at the splendid coastline and making mental notes to research 2025 holiday lets. And thermal underwear.The distance between this years whodunit players and the characters we know and care about is the issue. Yes, every series ofShetlandwelcomes a new guest cast, but when this show is at its best, that guest cast is properly entwined with our guys. Annie Bett may have been in Toshs Strictly WhatsApp group, but their connection is thinly sketched, as is the enjoyable-but-too-sparse rapport between Ruth and young Noah.In two episodes time, when this murder gets solved, what will have changed for the main characters? Unless it tuns out in a shock twist that Rev. Alan Calder shot the pair of them with help from Sandy, Billy and Cora, where will be the lasting impact? Tosh learning that its hard to police an island populated exclusively by people you went to primary school with? She knew that already.Now that Shetland has reabsorbed its prodigal daughter Ruth Calder, her development appears to have stopped. The tender story of her teenage years having been told last time, shes been demoted from character to function. Ruth now exists only to roll her eyes at suspects and look at them like a scathing headmistress in the atmospherically decorated interrogation room (Farrow and Ball colour: Puffins Breath). Id swap any number of scenes with Sad John Harris or the Tragic Jakobsons for a living, breathing conversation between her and her brother that lasts longer than a page of dialogue.Read more The Tragic Jakobsons were the major focus of episode four. Dad Stefans desperation to keep daughter Astrid alive is behind the whole business with the marine research facility. Once Ruth and Tosh had Mulder and Scully-ed their way down to Dr Mohans secret lab, and Cora had given her verdict (a marvel, that woman. Forensics to bioengineering to general practitioning Like Miss Rabbit inPeppa Pig, theres nothing she cant do), the mystery was solved,At Stefans behest, Dr Mohan has been developing and administering an experimental treatment for Astrid involving unlicensed human stem cells. The poor girl had had enough of the sci-fi injections, and was planning to run away to her birth mother in Estonia with Anton and his boyf Nathan. When her dad put a stop to that, she tried to stow away in the back of a lorry disguised as a box of ready-to-make prawn crackers, but her ailing health stymied that plan. Its all academic anyway, as Stefan isnt Anton and Annies killer.The list of potential culprits is narrowing to the point when only one suspect would make dramatic sense with two episodes to go, and hes not even a suspect: Young Noah Bett. If the boy did somehow pull the trigger on his mum and Anton, that would explain why he wont or cant talk about it, and why Euan Rossi is obsessed with the kid. Itd be in keeping with the rest of the deaths so far this series too brother kills brother, father kills son, little boy kills mum?Prof. Rossi was the subject of episode fours cliffhanger. Following a helpful reminder to us that the gun used to kill Annie and Anton was still missing, we watched as Rossi retrieved it from a storage locker. Hes dangerous, Ruths old flame from Thames House told her. Is he though, or is he just trying to protect Annies son?Shetland series 9 continues on Wednesday December 4.