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
A marquis named Walter, pressed by his lord to take a bride, marries and ennobles a poor young woman named Grisilde on the condition that she obey him in everything.
Act II
Having decided to test Grisilde's obedience and constancy, Walter arranges a series of trials, telling Grisilde, first, that she must consent to the murder of her two children, and then that she must leave the palace to make way for his new bride. He forces Grisilde to prepare his chambers for his new "wife's" arrival and asks her how she likes his new "bride."
Act III
When Grisilde replies that she likes Walter's new wife very much but begs him not to torment the girl the way he did her, Walter is finally convinced of Grisilde's constancy. He reveals that the two children who have arrived from Bologna are actually hers, whom she thought murdered. He reinstates Grisilde as his wife, and the family lives happily ever after.