Save the Cat. It is actually a book on screenwriting, but you don't need to be a writer to enjoy it. I zipped through it in a few hours. I just downloaded the sequel, which is perhaps more targeted at movie buffs in that it takes his framework from the first book and shows how 30 famous movies follow it.
The reason it is compelling is that it lays out the script formula -- down to the minute -- followed by a LOT of modern movies. I have seen the structure discussed in this book repeated in enough other books to be convinced that it is indeed the formula used by most writers, taught to most amateurs, and eschewed only by the most confident.
My wife's first reaction was: how limiting, to turn movies into repetitious formulas. There is in fact a substantial school of thought that Save the Cat has singled-handedly killed movie-making creativity. I understand and sympathize with that response, but remember that symphonies and sonnets and Shakespeare plays and Greek tragedies all have a defined "standard" formula as well. Here, for example, is the typical structure of a Sonata (many or even most first movements of symphonies are in this format) (source)
Even when artists violated these forms, they were familiar with the forms and knew they were violating them and were doing so for a reason. When you take Music 101, a lot of the time is learning these forms. So why shouldn't one do something similar in trying to appreciate film?
Save the Cat presents the movie version of this. Other books like this book provide a separate take. But what is amazing is not that they are different -- they use different terminology -- but how absolutely similar they are when you cut through the jargon, down to the script page numbers for each event.
PS- This may be one of those if you can't do, teach things. His book on writing screenplays is a bestseller, though he only had two movies produced from his work (he died fairly young) and one of these won a Razzie for worst screenplay of the year. To some extent, it all depends on how you define "success". He sold a couple of dozen spec scripts, which is the very definition of "not easy".