At the start, my professor is very temperamental. He is also currently in a state of depression from not being able to solve the puzzle. How can I get him from there to the plot point?
I begin writing scenes that will bring him from the depths of his depression to the meeting with this character. First then, I introduce a clue that wakes him from his lethargic gloom with a glimmer of hope and, more importantly for such a motivated character, a path forward where he previously saw none.
It is from here that the story will progress, scene by scene, until we reach the plot point, where he meets the second person and must convince her to supply him the information he needs.
Likewise, each scene connects with that before and after, and once that chain is built, written, and polished, I move on to the next big plot point. Think of it as climbing a mountain–once you have overcome the steep climb to reach the top, you look ahead to the next mountain and begin that long journey.
Don’t worry–It’s much harder than it looks, but it is a lot of fun.