My story developed a plot hole, a big wide one that I couldn't find a way around. One of those moments where you go, Oh, DUH, *that* wouldn't happen. Why would they want her to go to trial and bring embarrassment to them? And why would they shoot the guy instead of poison him or try to make it look like an accident?
I brainstormed, just writing out likely scenarios and answers, trying to think a way around the hole. I've decided the main target of the assassination isn't my protagonist after all, but her companion. And now they're more than casual friends, and are in a conspiracy together. My protagonist turns out to be in the wrong place at the wrong time and embroiled in a plot that forces her to go on the lam. Think, The Fugitive, except with a female, and except that the story is about the murder, not about her life on the run. so yeah.
Now I have to go back and basically re-write the whole story. I thought at first that I'd just need to amend the beginning and the conversation where the plot is shown, but now I've decided to change the identity of the murderer, and bring her into the opening scene. So yeah. New beginning it is. And pretty much new middle.
The funny thing about all this is, I actually had a plot all put together from the very beginning for this story. And only when I was getting to the climax did I discover Major Plot Hole #1, which led to more tripping and more holes. And now it's start all over again.
The moral of the story? Plan all you want, but in the end, writing is all about knowing when to drop the passing game and learn to punt on the run--and if all else fails, stuff the football in the hole until it sticks.