Hmm I haven't tried this myself but they used it in the main game so you can try look at thosde files and see how they did it, but i imagine it could be something like.
you enter the scriptarea, player gets inactive. you force player to look at monster, the monster walks towards you, he comes to you, and when the monster enters the scriptarea you're in, the the screen fades to black and you load the map in a prisoncell or whatever you had planned
I can't make the script for you but that's basically what I imagine would be fitting. Maybe other guys around here could help you with that. I'm not so experienced yet.