My first Harry Hole novel was `the Redeemer', an odd place to start, but the book was in Sainsbury's, so I bought it on impulse. It was excellent, so I then bought `the Redbreast', the first of the Oslo books, but now the third book overall, as the two books originally only available abroad are now in English too.
So `Cockroaches' is the second book.
I looked forward to both `the Bat'(the first book) and this second book, and although both are very good, they are not, for me, a patch on the later books, all set in Norway.
In the same way as Morse away from Oxford was never the same, or Wallander out of Ystad, Harry Hole is a product of Oslo, and it is in his native Norway that we get his full character and personality traits that make him such an appealing, if flawed, man.
In Cockroaches he has been once again sent abroad to solve the murder of a Norwegian national, this time the Ambassador. The action this time takes place in Bangkok, Thailand, and the atmosphere is well drawn, giving us the feeling of claustrophobia and suffocation of the overcrowded and polluted Thai capital.
We get hints of Harry's background, and his demons, but as in `the Bat', set in Australia, I felt as if he was far more superficial a character than in the Oslo novels.
If you are coming anew to Jo Nesbo's Harry Hole novels, by all means read them in order, starting with `the Bat', then Cockroaches.
But I would suggest that you would probably find starting at `the Redbreast' just as fulfilling, and you would not miss any information about Harry that you don't find out later.
And once you have read `the Redbreast' you will have to read the rest of the books, they are addictive!