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
This act is split into two parts: 1) The barbershop scene in which the plot to go after Will Mayes is hatched; and 2) The foray into Minnie Cooper's past, and the details of her present existence.
Act II
The second act is likewise divided into two parts: 1) Will's abduction and Hawkshaw's leap from the moving car; and 2) Minnie's walk through town, her breakdown in the movie theatre, and the subsequent laughing-screaming fit she has when back in her bedroom.
Act III
The drama ends on an ugly note in Act 3, wherein McLendon arrives home at midnight and physically and psychologically abuses his wife, a character we meet for the first time at the end of the story.