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
Bigger chickens out of committing robbery, finds a job, is embarrassed by his employer’s daughter (Mary) and her boyfriend’s attempts to treat him as an equal, and accidentally kills Mary. He stuffs her body in the furnace to hide the evidence of his actions.
Act II
Bigger makes plans to get ransom money from the Daltons, who are worried about their missing daughter. Mary’s body is discovered and Bigger flees, knowing the gig is up and his guilt will soon be known. He kills his girlfriend Bessie to keep her from talking to the police, then tries to hide from the men searching the city for him. Eventually he’s caught and taken to prison.
Act III
Jan arranges for Bigger to have a lawyer, Boris Max, who makes the argument that Bigger’s actions were socially conditioned responses to a situation that he couldn’t control. He tries to reduce Bigger’s sentence to life in prison instead of the death penalty, but he fails. Bigger realizes what his life is worth just as his life is ending.