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
Peter, Susan, Edmund, and Lucy arrive in Narnia, discover that their friend Mr. Tumnus has been arrested, and decide that they must rescue him.
Act II
Edmund betrays his brother and sisters to the evil White Witch. The Witch lays claim to Edmund's blood and Aslan is forced to sacrifice himself in Edmund's place.
Act III
Aslan is miraculously resurrected, the battle against the Witch is won, and the four children are crowned Kings and Queens of Narnia.