On the last day in the room, the writers debated what should happen when Elena sees Mia’s piece. “What if we make it a comment on race and class?” Tigelaar asked her diverse group of writers. Attica Locke, one of the writers, noted that “The fact that you can separate race and class from motherhood is a privilege.” There was talk about having Witherspoon’s Elena dismantle the bird cage as an act of liberation, but another writer, Shannon Houston, objected: “I really don’t like a story that ends with a white woman destroying a black woman’s art.”

Tigelaar said “it was a truth that’s hard to hear, and it really changed how we viewed the ending.”

During a phone interview, she discussed why the writers diverged from the book at key moments (the ending, the abortion story line) and how an act of arson freed the characters from themselves. Here are edited excerpts from the conversation.

In the book, readers learn right away that Izzy set the “little fires everywhere” that burned down the Richardson house. But in the show, Izzy intends to start the fire but it’s her siblings who actually ignite it. Why did you make that change?

Celeste Ng’s book is so beautifully nuanced, and it was a real challenge to figure out how to bring to life the interior thoughts, the prose, the back stories. I felt like the ending was a place where we could go even deeper into the layers and the complexity. While we certainly didn’t want to rule out the possibility that it could be Izzy, we had an opportunity to create this mystery — that it could have been anybody. At first, I started kicking around the idea that it could be Elena, because that would be taking a character to the furthest point. But we wondered if that would be believable. So then I kicked around different ideas about the siblings: Could it be Lexie? Could it be Moody? Could it be Trip? And then I thought, “What if it didn’t have to be one person? What if it was all three?”