No one knows you like your book club.

High school English teacher Polly Goodman can talk about everything and anything with the women in her book club, which is why they’ve become her closest friends and, along with her veterinarian husband, the bedrock of her life. Her students, her fraught relationship with her mother, her struggles with IVF—Polly’s book club friends have heard about it all.

But when they give Polly an ancestry test kit as a joke, the results match her with a stranger. It is clear to Polly that this match is a mistake, but still she cannot help but comb through her family history for answers. Then, when it seems that the book club circle of four will become three, Polly learns how friendships can change your life in the most profound ways.