Writing Fiction - Part I is here.
The setting for your fiction work needs to be interesting. It could be be a peaceful idyllic place where the order of things has been disturbed by a brutal event like a murder, or it could be a bad corrupt world where wrongs happen in every dark corner. You need to take the reader into this new world and have him wanting to return again and again. Do not fill him with details and lose the point of the book which is solving the crime but make him familiar gradually with this new perspective on the hero's world.
Good advice from Carolyn Wheat is "Write what you love", deconstruct the books you read. What did you like in this book? Was it the new world you discovered? Was it the obscure scientific fact that made what was on first sight impossible, possible and plausible? was it the protagonist's overcoming his human failings and succeeding?
Think from the criminal's perspective. What made him commit the crime? how did he plan for it? how did he cover himself? did he get the right guy? is he an insider or outsider to the protagonist's world? Is he still active and commiting more crimes? Once that is clear you can shape your story from the protagonist's view.
The event that the story revolves around does not need to be a crime, it could be a heart broken and the girl's way of getting revenge and finding her prince charming all at the same time. It could be someone righting a wrong in a corrupt world.