High Level tools for GTA-style mission style - PlayMaker? uScript?

In GTA, for example, you have play a protagonist who is assigned multiple missions - he's in a sandbox, but he has a destination to trigger the mission start - then he voluntarily engages in the missions, with hinted and explicit guidance and cascading triggers.

This is essentially what I want to do on my current project, which is not a game, but a simulation where the user will do something similar - get on a bus, he has confrontation, only then the bus starts to drive on a path, the user chooses responses from an RPG style dialog menu perhaps - his actions will drive what happens next.

He repeats until he has resolved to scenario properly.

Its all very much a state management situation, so I am guessing PlayMaker might help - I am also looking at uScript. I did my first Unity3D project in code, but because of the iteration which will be required on developing this simulation, I want to work at a higher level.

If there are any other suggestions for any parts of this, they are greatly appreciated.