el guión de nuestro hilo expositivo = the thrust of our exposition/argument

I think if you try to be too literal here, it will end up sounding odd, and that this is what an English speaker would write in an equivalent context.

Thrust = the principle purpose or theme of a course of action or line of reasoning (Oxford). I think it can account for both 'guión' and 'hilo' here.

the outline of our expository thread (literal translation) = the thrust of our exposition, in my view