I love the detective too, Jimmy Perez who comes from Fair Isle (like the sweaters). His decidedly un-Scottish surname and Mediterranean looks are due apparently, to the fact that El Gran Grifon part of the Spanish Armada of 1588 is wrecked off Fair Isle.
This book is the sixth in the Shetland series. There is also a tv series based on the books starring Douglas Henshall. I enjoyed the tv dramatisations despite the fact that Douglas Henshall looks nothing like Jimmy Perez and that characters and plots and even murderers were changed extensively. The one thing that wasn't changed was the beautiful location.
Life is good when things match.