The island of Unst is the most northerly inhabited island in Britain. Visit, and you find yourself tripping over a series of "most northerlies", from the brewery and the castle to a church and a nature reserve. Now, with "Thin Air", Ann Cleeves has given us what is very probably Britain's most northerly murder mystery.
A group of friends who met at university have travelled north from London to Unst to attend a hamefarin', a party to celebrate the wedding of two of the group. Caroline and Lowrie were married near her home in Kent, but have now come to Unst to celebrate with his friends and family. But after the party one of the group, Eleanor, disappears into thin air, leaving just an email: "Don't bother looking for me. You won't find me alive." Detective Inspector Jimmy Perez and Detective Chief Inspector Willow Reeves head north to join the search, and then Eleanor's body is found.
Unst is an island which, to the outsider at least, conveys an air of quiet calm; a sense of a community in which everyone knows everyone else. It certainly seems the last place on earth you would expect a murder to take place, which is one of the things that make it such a great setting for a murder mystery. The calm pace of life on Unst dictates the pace of this most measured of novels: but as the action moves forwards, the underlying tension grows steadily in a beautifully unsettling way. Before her death Eleanor claimed to have seen the ghost of a local child who drowned in the 1920s, and afterwards her friend Polly also does so. Who was responsible for Eleanor's death? Was it one of the visitors? Or could it have been an islander? As the plot develops the number of possible motives multiplies, and the conclusion, when it arrives, is both unexpected and satisfying.
"Thin Air" is the sixth book in Ann Cleeves' "Shetland" series, but don't let that put you off diving into the series at this point. The characters are beautifully developed and you don't need to know what has happened in the earlier books to gain the maximum enjoyment from this one.