This will be my fourth NaNo (non-consecutive), and I'm fairly confident I can add my third finish this year.
I normally outline heavily, and while I didn't put nearly the time I wanted into that project this year, I think I'll be all right. I'm adapting a short-form thing I wrote a couple of years ago into a larger story, because I always thought there was a little more meat there than I had time to really play with.
In this case, the story is a superhero-metahuman setting. The main character is a woman who was "normal" while her sister was the one with extraordinary abilities. The thing is, the sister, while fundamentally moral and a nominal hero type, has profound misgivings about the idea of not being human (or, at the very least, something other than human), something that leads her to be self-destructive when she doesn't have a Big Bad to fight. In an effort to prevent or delay that, the point of view character chooses to make herself into that sort of persistent Professional Adversary. The story starts on the day that wasn't enough.
Right now the plan is for the first bit to be an in medias res start, then I'll probably do the "how we got here" contextualizing story that sets up the midpoint of the story before getting on to the consequences and blah blah. I'm reasonably sure there won't be a "nominal bad guy teaming up with the nominal good guys" arc; the main character is going to be strongly antagonized by her sister's former...um...co-workers, while also dealing with what happens after the sister's real dive into her downward spiral.