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I see that everybody wants to have OP's GM. Not unexpected, it seems like a nice riveting story-line (well-paced and well-measured, as in a TV series rather than a movie) It's not that hard, honestly. The big thing here is the twist. That delicious, ethically inverting twist. The one that makes the players think about just what the hell's going on between themselves and the setting.
Again, not that hard.
Pick the twist ahead of time. I know, planning in advance for PC's is hard, but you've got to do it if you want something like this. Keep it simple, like, 'the PC's end up fighting their own people', or 'a player must battle their own daughter' (for examples).
THEN, work backwards. Figure out the Why/Who/Where/How of it and make sure to weave it into story developments. As long as you've got a central story-line (I hope to god you do if you're table-topping in general), it shouldn't be that hard to eventually lead the players into it. That way, you keep the proper foreshadowing to prevent it coming out of nowhere and seeming like a bunch of nonsense, and you still get the nice kink in their perceived story-line.
If they end up going down a different plot track entirely, though, that's when it threatens to be completely bypassed, as PCs are not the most predictable creatures. Fear not! If the twist is simple enough, it can simply be retooled and foreshadowed differently so that you still end up with something along those lines. As long as they don't go perpendicular to the story (side quests, side quests everywhere) or the other way (lol characterization inversion), you should still get far enough in the plot so that you can have it happen.
Just some food for thought that hopefully does a little good, so you too can become the weaver of stories that are, fates willing, told time and time again.