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.
Act I
Eustace Scrubb is magically transported to Narnia along with his cousins Edmund and Lucy Pevensie. Eustace meets King Caspian and joins the voyage of his ship the Dawn Treader, but remains critical of everything he sees and experiences in Narnia.
Act II
Eustace is transformed into a dragon. His experience teaches him about his own flaws and self-interest.
Act III
Restored to human form by the lion Aslan, Eustace gradually begins to change into a brave, loving, good-hearted adventurer like his cousins.