Mrs D do enjoy "Dead Water".... the fifth Jimmy Perez novel by Ann Cleeves. An adaptation from the series was recently televised as "Shetland" starring Douglas Henshall. (Who I do remember giving a very fine performance in Denis Potter's "Lipstick On Your Collar" alongside Ewan Mc Gregor).
Ann Cleeves also writes books featuring Vera Stanhope aka "Vera".... another successful TV series this time with Brenda Blethyn in named role.
You can read a review of "Dead Water" overhere at Euro Crime....
and watch the trailer for "Shetland" on the sister Euro Crime Blog here.