“At this moment, I think Briony knows that she’s gonna read it. And if she takes it, she’ll read it. I think that’s the worst thing that Briony does, is that moment, actually. I think that she actually believed that she saw Robbie, later. But I think the taking of this letter, with the knowledge that she’s gonna open it and read it, is one of the worst things she does. Her biggest mistake.”

Dir. Joe Wright, Atonement commentary