For a three-act plot analysis, put on your screenwriter’s hat. Moviemakers know the formula well: at the end of Act One, the main character is drawn in completely to a conflict. During Act Two, she is farthest away from her goals. At the end of Act Three, the story is resolved.
Satan plots revenge in Hell (Books 1-2).
Satan is kicked out of Eden (Book 4); Raphael and Adam have a long talk (Books 5-8).
Adam and Eve eat the fruit and are forced leave Paradise (Books 9-12).