Alright, I know this is a basic recommendation, but you can’t skip 'The Anatomy of Story' by John Truby. It’s the book I lend to friends who ask me this exact question, even though they rarely give it back. I’ve read a bunch of the usual suspects, but Truby’s breakdown of the 22 steps and his focus on moral argument and desire just clicked for me in a way Syd Field’s structure stuff never fully did.
Some of the newer, flashier books feel like they’re repackaging blog posts. 'Anatomy' is dense, almost textbook-like, and you’ll need to take notes. It’s not a breezy read, but it fundamentally changed how I approach outlining. I remember struggling with a protagonist who felt flat, and his chapters on the ‘moral flaw’ and ‘ghost’ gave me a concrete way to fix it. For a more modern, industry-savvy companion, I’d pair it with 'The TV Showrunner’s Roadmap' by Neil Landau. Less about pure theory, more about the real-world process of breaking a season and running a writers’ room.
Honestly, skip the ‘guru’ books with the hyperbolic titles. Find the ones working writers actually cite in interviews. Truby comes up constantly, and for good reason.