After reading, in quick succession, the classic texts on screenwriting by Syd Field, Robert McKee and John Truby, I didn't expect to find another text on the subject that would surprise me. I was wrong. Alternative Screenwriting, which I read in this 5th edition, heavily revised and expanded from its original 1990 version, picks up where the other books end, and builds a strong case for itself: that despite what you may have heard about Hollywood-centric scriptwriting (and any form of popular storytelling for that matter) there is a wide range of styles, structures and voices to be aware of if you want to have a complete storytelling toolset.
It starts from the classic 3-act structure and builds up from there to all alternatives in terms of plot, character, perspective and narrative involvement.
The book may be hard to follow if you are not familiar with many of the (sometimes obscure) movies referenced, but it provides enough case studies for each of its discussions on structure, genre and voice as to defend its views with confidence. And even if you dont't fully agree with the authors' arguments (at times ideologically biased) they are thought-provoking nonetheless, and achieve the book's main goal: to challenge the assumptions and limitations of other screenwriting texts (which are explicitly referenced and acknowledged as required learning) and to develop an urge to go beyond well known patterns and find your own voice.
A much appreciated addition to my storytelling library that I wholeheartedly recommend - but probably read McKee, Field and Truby first, or you won't fully get the "alternative" part - alternative to what?