Rachel is living alone in Philadelphia, working 16-hour days and isolating herself after a devastating breakup with Sam.

Rachel spends a day riding the city buses with Beth as research for a magazine article.

Rachel attends Beth's annual Plan of Care meeting and sees the full picture of Beth's independent life for the first time.

At the end of their day together, Beth asks Rachel to ride the buses with her for one full year.

Rachel meets bus driver Tim and learns how he finds meaning and beauty in the details of daily life.

Bus driver Jacob shares the story of his near-death experience and how it transformed his faith and values.

Rachel joins Beth and Jesse for lunch at a restaurant where a hostile customer glares at the interracial couple.

Rachel sits in the waiting room with Jesse during Beth's sterilization surgery, feeling guilty about her role in the decision.

Rachel researches intellectual disabilities for the first time and has a fundamental shift in her understanding of Beth.

Bus driver Bailey tells Rachel the story of the optimistic boy who knows there must be a pony somewhere.

Rachel and Beth ride with Rick, flirting effortlessly while working together on his crossword puzzle.

Jacob drives Beth and Rachel to the hospital for Beth's eye surgery; Rachel feels a sudden rush of love for her sister.

Rachel accepts Rick's long-standing dinner invitation and discovers they have a natural, effortless connection.

Beth tells Rachel the year is over; Rachel watches the bus drive away and chooses not to get on.

On her wedding day, Rachel finds a congratulatory letter from Beth tucked into the corner of her mirror.

Rachel Simon begins the year as a lonely, workaholic writer who has long been neglecting her intellectually disabled sister Beth. She agrees to spend a full year riding the city buses with Beth and gradually meets the drivers who form the heart of Beth's community. Through these encounters, Rachel begins to confront her own isolation and her failures as a sister. A turning point arrives when Rachel finally educates herself about intellectual disability and gains a new compassion for Beth. The year culminates in Beth's eye surgery, where the act of caring for her sister cracks open the emotional ice Rachel has carried for decades. By the story's end, Rachel has healed enough to open her heart, marry Sam, and stand fully behind her sister.

The core journey of two sisters reconnecting through a year on the buses.

Sam proposes to Rachel, but she cannot say yes and does not fully understand why.

Rachel publishes an article about riding the buses with Beth, sparking regular communication between the sisters.

A rude passenger challenges Beth's bus pass, and driver Jacob steps in to publicly defend her.

Beth grows furious with Rachel for moving too slowly to keep up with her morning bus routine.

Driver Rodolpho reveals how his obsessive pursuit of wealth cost him his family and his first marriage.

Driver Henry grows tired of Beth riding his bus for hours every day, and the tension nearly causes a fight in the break room.

Beth writes Rachel a letter asking her to marry a bus driver so she can have one as a brother-in-law.

Rachel receives a letter from driver Rick, written at Beth's encouragement, inviting her to dinner.

Rachel attends a conference on self-determination and hears professionals debate the right of people with intellectual disabilities to direct their own lives.

Jacob invites Beth and Rachel to spend a summer day at the Jersey shore with his family.

Rachel tickles Beth's arms and back while they watch TV together, and they go the whole evening without an argument.

Rachel rides with driver Melanie and realizes she has let her own friendships erode through years of overworking.

The bus drivers begin turning to Rachel for personal advice and emotional support with their own life struggles.

Rachel yells 'I hate you' at Beth during a fight and immediately regrets what she has said.

Beth and Jesse eventually break up after years together, and Beth cries every night until her community helps her heal.

Before the bus year begins, Rachel's inability to accept Sam's marriage proposal reveals how emotionally shut down she has become. Through smaller moments across the year—Beth's frustration with Rachel's pace, conflicts in the drivers' break room, and Beth's secret matchmaking scheme—Rachel's world slowly expands. She witnesses the complex social dynamics of Beth's community and begins absorbing the wisdom of drivers she once dismissed as background characters. Beth's matchmaking eventually nudges Rachel toward a first date with Rick, cracking open her long-frozen heart. As the year winds down, Rachel is forced to confront her own cruelty toward Beth and must choose between pride and reconciliation. The arc closes years later with Beth and Jesse's breakup, a reminder that Beth's life continues to evolve well beyond Rachel's influence.

The quieter moments and secondary encounters that slowly shaped Rachel's transformation.

Baby Beth stops breathing during infancy; seeing her daughters watching jolts their mother back into action and saves Beth's life.

Their mother tells Rachel and the siblings that Beth needs extra help and that her condition could have happened to any of them.

Rachel forces Beth to change the TV channel and accidentally watches Geraldo Rivera's exposé on Willowbrook State School.

Beth dresses as a cowgirl and shoots water guns at Rachel's school bus; the other students mock her relentlessly.

Rachel calls Olivia to ask what intellectual disability really means and learns that Olivia finds Beth a joy to work with.

Rachel learns about the self-determination movement and begins to see Beth's refusal to work as a courageous exercise of civil rights.

Beth disappears after their mother leaves with her new husband and sends no word of where they have gone.

Rachel becomes an insomniac at boarding school, spending months unable to sleep while waiting for any news of Beth's whereabouts.

Beth arrives at the airport filthy with her hair falling out and tells her family she was held at gunpoint.

Rachel calls her estranged mother from a hotel room during a work trip; her mother gasps and cries with relief.

Rachel and her siblings take Beth to a restaurant for a tearful first reunion with their estranged mother.

Rachel's father visits each of his three children and asks them to take Beth part-time; all three refuse.

Rachel refuses to answer Beth's calls or open her letters after their fight, then realizes she is being self-righteous and cruel.

Rachel retrieves Beth's Christmas gift from her trunk and opens a carefully made scrapbook filled with a loving letter inside.

Rachel speaks at a university disability studies center and is told that her memoir is a book about social justice.

The childhood flashbacks reveal a family fractured by a depressed mother and an absent father, whose neglect left all the children struggling to connect with one another and with Beth. The most harrowing revelation is the months when Beth vanishes with their mother's abusive husband, an experience that scars the whole family and may have fueled Beth's later determination to ride buses freely and safely. Rachel's long estrangement from her mother and her guilt over refusing to help her father care for Beth explain the emotional distance she carries into adulthood. Key moments of discovery—learning what intellectual disability really means, and encountering the self-determination movement—crack that distance and transform Rachel's view of Beth from a burden into a civil rights pioneer. The final turning points come in December when Rachel must choose between pride and sisterhood, and she chooses correctly. The arc closes with Rachel standing before an audience and realizing that her deeply personal memoir has become a public act of advocacy.