If you're running a plot and aren't open for change, then you should go to a game where you can be OOC and controlling, I think.
For instance, in the one that I've been slow-burning recently, there have been several instances of change, and the characters have really had to think outside of the box to make things happen.
I find that in these scenarios, you need to be IC, because just like in real life, if your character really desires something, he or she will do things to get them, correct?
There was once a good RPer several years back who only had one goal, one plot. After the first few tries it became obvious what he was after, but he kept coming up with different ways to try and get there. It was quite effective, and after a while it was funny, and a little bit exciting to guess at what he'd try next.
So if you're able to thwart someone's 'plot', good for you. It's up to them at that point whether the RP is dead or not, no? Because in essence, all it is, is certain people having different goals, and sometimes they work, sometimes they don't.
"We do not control extenuating circumstances. All we control is our reaction to them." IC and OOC.