Here's the one I wrote for modern Call of Cthulhu:
http://www.javaop.com/~ron/tmp/CoC.pdf (password-protected since it's still being run -- let me know if you want the pass)
I don't think it'll be useful to run, but it'll give you some idea of how I plan things. Basically, there's a story going on around them. This story is going to run more or less to completion, whether or not they get involved. They can influence it, but more or less it'll push forward.
With that story in mind, I made up a calendar (on paper, I don't have an e-version). I put all the important events that would happen, and picked dates for each of them.
Next, I wrote a bunch of encounters. Some are designed to happen at a specific time, others can happen whenever the players trigger it. That being said, they are all generic enough that they can be shuffled around if necessary. I find that when running it, the players will back me into a corner and I need to pull out an encounter at a different time than it was supposed to.
At some point, I also fleshed out the NPCs, important locations, etc.
By the time I've written it, I've read the story over 10 - 20 times, and I have a firm idea of exactly what happens and when. If a player does something totally unexpected, I can easily compensate just because I know the story so well. I find that in pre-written stories, that doesn't work so well since you probably don't understand every aspect of what's going on.
That's my theory of running games, hope it helps! And if anybody wants the password, like I said, just ask.
