Almost sounds like a Realty TV show, doesn't it?
But for me, plot evolution is all about what writing a novel is about. I'm a pantser, which means I write with no outline and little prep work. Sometimes I write a blurb, sometimes I write down 1 page of facts or ideas, and sometimes I just have a character name. Either way I write fast, rough drafts are dirty, gritty, and full of intense raw emotion. And when I start, I have little idea where I am going.
It is kind of like chess, because I usually know about 3 chapters ahead where I am going. But once I get those 3 chapters written, well, all bets are off. What happens next? Not knowing what happens in your plot next is a lot like driving blind or sky diving blindfolded, yes those might be more dangerous. And that's exactly how it feels to write as a pantser. Adrenaline rushes happen. When that perfect piece of information hits you that will drive your story on, make it more complicated, a twist not even you saw coming, man that feeling is not beat by anything!
Then you look at your story and realize you foreshadowed this event through your entire book and you DIDN'T"T EVEN KNOW IT. It's like you are a writing God. A genius. Until you slam into another wall and have no idea what to do next. Then you're back to hating yourself, but I digress...
When I started 15 MINUTES, I had one sentence in mind. "I HAVE 15 MINUTES..."
That's it. That's all I had. I knew it was time travel, but that was it. I didn't have a situation, a danger or even a character name. But I sat down and started writing anyway. About half way through chapter one, I came up with the characters name, Lara Crane? How? It just came to me. And seemed like a nice name, so it stuck.
I knew she was a teen girl and was risking everything to change the past. Why? How come? Those were the questions that shaped the plot.
I knew when she returned from the past, her life would be changed forever. I thought perhaps she'd be wanted for murder, on the run, with the police on her trail and she'd have to piece together why and what happened. A good plot, and one I would want to write, but not the plot that this book ended up with.
In some ways, the book is smaller and more personal. If you strip away all the intrique, and time travel you have her a book about a teenage girl who struggles with the relationship with her mother. She wanted nothing but a relationship with her, but when Lara gets it, she finds her mother is flawed. Not the woman she put on the pedestal all her life. And what girl (or woman) can't relate to that?