The following version of this book was used to create the guide: Strout, Elizabeth. Oh William! Penguin Random House LLC, 2021.

Elizabeth Strout's novel Oh William! is written from main character Lucy Barton's first person point view. The novel employs both the past and present tenses, as it meanders through time and space. The unconventional narrative structure defies typical notions of plot and linearity in order to enact Lucy's complex psychological terrain as she attempts to process her grief. The following summary primarily relies upon the present tense and a linear structure.

Two years after her second husband David dies, Lucy Barton is still struggling to process her loss and grief. Because grief feels so lonely, Lucy decides to tell the story of her first husband William's recent sorrows. Even as Lucy describes William's experiences, however, allusions to and memories of her past life creep onto the page.

When Lucy is a little girl, she lives in Illinois with her parents and siblings. Their home is diminutive and the family has very little money. Lucy's mother is perpetually violent. Her father suffers from post-traumatic stress disorder, which leads him to inappropriate and unpredictable sexual behaviors. Lucy does not feel loved throughout her upbringing. When she gets ready to leave for college, she is overcome by fear. Her life has been so alienated and insular that she cannot imagine entering an entirely unfamiliar world.

During her sophomore year at college, Lucy meets William. He is working as the teaching assistant for her biology course. As their relationship develops, Lucy realizes that she feels a sense of comfort and security with him that she has never felt with anyone else. The longer they are together, the more Lucy relies upon William's physical and emotional closeness for stability. William relies upon Lucy for similar things as well.

Not long into their marriage, Lucy develops a kinship with William's mother, Catherine. Catherine sees and accepts Lucy in a way most people do not. She loves being around Catherine, and appreciates the way Catherine encourages her into new experiences. Catherine is also wealthy, unpretentious, and generous. Catherine later gets sick and dies. Years later, Lucy will wonder if her death inspired William's infidelity.

Though Lucy becomes privy to William's cheating, neither she and William want to end their marriage. They have become so dependent on one another, they fear what their lives would look like otherwise.

Even still, after roughly 20 years of marriage Lucy begins to realize that her marriage is suffocating her. Her intimacy with William feels like a trap. She decides to leave him. Because they have two daughters together, Becka and Chrissy, and because of their deep history together, Lucy and William remain friends.

Over the years following, William remarries twice. With his third wife, Estelle, William has another daughter named Bridget. Lucy likes Estelle and Bridget and appreciates their ability to all get along.

Then one day not long after David's death, Estelle unexpectedly leaves William. He calls Lucy for support. He has also recently discovered that his mother had another child before him, who she abandoned as a baby. William does not know how to deal with either of these issues without Lucy. Recognizing William's distress, Lucy agrees to accompany him to Maine to find his half-sister.

During their trip together, Lucy begins to reflect more deeply upon her childhood, her relationships, and her identity. Her experiences with William make her realize that their relationship must change. She also learns to reconcile herself with her former trauma.