Stop a unit from moving without changing anything else?

Level 6
Dec 9, 2014
One of the more often occurring things in my map is going to be dialogs with certain npcs you come into contact with. During these conversations I'd like it so that the hero isn't able to move away in the middle of a dialog and make it awkward to be 100 yards away still talking to an npc like nothing's wrong lol. Is there a way I can stop their movement then give it back later when I need? I've thought about using the cinematic mode for these dialogs but I don't know how well that works with showing dialog windows and what not, also, I like the fact that it's adding the text to the log so that in case you miss something you can go back and look. Suggestions?