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
Jim meets Ántonia and the two become friends; the Shimerdas manage until a tough winter leaves them out in the cold, and Mr. Shimerda commits suicide.
Act II
Jim moves to town. Ántonia, Tiny, and Lena become the center of the social scene. We get lots of drama and lots of sexual tension.
Act III
Jim goes off to college. He and Lena date for a while before he leaves her to study at Harvard. He visits Ántonia and we learn what's happened to her in the meantime. Jim then goes away for twenty years and returns to see Ántonia again.