One of my goals as a writer has been to write a fantasy mystery novel ... not in the sense that has become so popular and even hackneyed, where magic enters an otherwise contemporary detective story, but in the opposite sense: a fantastic secondary world setting gains itself a detective. (The previous idea would follow in a similar vein.)
This was my first concept for a novel-length project. It's (very) loosely based on a roleplaying scenario I ran and a short story I followed it up with, but the specifics and even the general elements have evolved so much that I'm comfortable calling it a new concept ... at least, new in the sense that I've never written it before, because it's been sitting in my next projects lists for a while.
The basic plot is that a mage who champions the rights of familiars is murdered ... leaving her familiar and apprentice to solve the crime. In mystery parlance, the familiar is the detective, the apprentice is the sidekick. I have an underdeveloped idea that the familiars have a society of their own. I have not firmly decided whether they are summoned or created, which is going to have a huge impact on the detective ... and whether I decide to tell it from her POV or the apprentice's, ala Watson.
(It's a huge decision: the familiar is going to be somewhat inhuman. Do I want to "distract" from the mystery by getting into her head? On the other hand, the idea of looking at human society as an outsider really excites me. On the third hand, I did have a romantic subplot in mind for the apprentice, which would be difficult without showing her perspective. For some reason, I am instinctively reluctant to consider a dual-POV story. Rather than giving me the best of both worlds, I think it would just dilute either effect. Do I do the classic detective "outside the brilliant mind" scenario or the "inside a weird outsider's head" scenario? ... I guess one is a mystery slant, one is a fantasy slant.)
I'm very confident in this setting and elements, but all those unanswered questions above ... and I'm concerned that I will end up retreading old ground, with my love of conspiracy and politics. On the other hand, that's what I love and (I hope) do well. So it's a conundrum.