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 lasts from the trial to the time where Grant finds himself stuck going to the prison to visit Jefferson on his own. A plot is formed when Grant's aunt and Miss Emma join forces to get Grant to make Jefferson into a man. He really has no choice but to obey.
Act II
The second act starts when Grant begins seeing Jefferson alone and ends when he argues with the Reverend over what their job/s are. The characters are moving far from resolution. Grant gets Jefferson to open up by buying him a radio, candy, and a notebook to write in. He wants him to be comfortable. The Reverend is the polar opposite; he thinks that the radio is a "sin box" and that the most important thing is Jefferson's soul.
Act III
This act is comprised of Jefferson's final days, which he chronicles in the notebook Grant gave him, his execution, and the response of the other characters to Jefferson's death.