I almost gave up on this book in the early part. The only reason I can think of was the lack of familiarity with German ranks, police departments and names - fortunately there is a basic glossary at the start just after the maps of Hamburg. Once I got used to them the story started clicking well.
Something isn't right in Hamburg. Two gruesome murders with emails from the killer to the senior police officer in charge (Erster Kriminalhauptkommisar Fabel) but there is no forensic evidence to make suitable headway. As an aside there is a persistent female journalist trying to get in touch with Fabel whom he ignores until too late. Organised crime and local politics eventually seem to be involved but to what extent is not initially clear. Worse is to come when the German equivalent of MI5 is discovered to have people involved and they have been holding back information leading to more deaths. Life becomes more complicated for Fabel and his team as they start to unravel the thread tying the crimes together. More detail? Read the book, it's worth it.
This is a good read for a first book with a sequel, Brother Grimm, coming soon. Once you become comfortable with the various terms and attitudes the book settles well and is quite enjoyable. It's well worth buying to escape from the usual American and British based crime books.