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
Act I of The Black Prince covers Part 1 of Bradley Pearson's narrative, "The Black Prince." In it, Bradley moves through a series of misadventures as various personalities interrupt his plans to take off for the summer and write a great novel in solitude. By the end of this first act, Bradley's incipient love affair with Rachel Baffin has fizzled out, and a new and entirely unexpected thing has happened to him—he has fallen in love with the much-younger Julian Baffin, Rachel's daughter.
Act II
Act II of The Black Prince covers Part 2 of Bradley Pearson's narrative. In it, Bradley moves rapidly from the initial ecstasy of his newfound love for Julian Baffin to "the pangs of disprized love" (as Prince Hamlet calls them in Hamlet, Act 3: Scene 1). Luckily for Bradley, he soon discovers that Julian loves him back. Unluckily, he's soon confronted with the wrath of Julian's parents. Not a bad string of achievements for a time span of less than two weeks.
Act III
You guessed it, Shmoopers: Act III of The Black Prince covers Part 3 of Bradley Pearson's narrative. In it, Bradley and Julian flee to the northern seaside cottage that Bradley rented as a writing retreat for the summer, but they don't enjoy their love nest for very long. In practically no time at all, Bradley's sister, Priscilla Saxe, has died, Julian's father, Arnold Baffin, has arrived to whisk Julian away, and Julian herself has run off into the night.
Back in London, it isn't long before things get even worse for Bradley—in short order, Arnold Baffin is murdered, and Bradley is arrested and accused of killing him. Everything that happens after that is set apart from the action of "The Black Prince" itself, but Bradley does give us a general summary of events in his postscript to his story.