What Makes a Great Screenplay?

Once upon a time, in such and such a place, something happened." In basic terms that's about it – the very best definition of a story. What an archetypal story does is introduce you to a central character – the protagonist – and invite you to identify with them; effectively they become your avatar in the drama. So you have a central character, you empathise with them, and something then happens to them, and that something is the genesis of the story. Jack discovers a beanstalk; Bond learns Blofeld plans to take over the world. The "something" is almost always a problem, sometimes a problem disguised as an opportunity. It's usually something that throws your protagonist's world out of kilter – an explosion in the normal steady pace of their lives: Alice falls down a rabbit hole; spooks learn of a radical terrorist plot; Godot doesn't turn up.