One Day (2009) is a romance novel by British novelist and screenwriter David Nicholls.

The novel traces the relationship of Emma Morley and Dexter Mayhew across two decades, beginning on their graduation day—July 15, 1988. Each year, on the same date, the story revisits them, chronicling the evolution of their friendship, the progression of their careers, and the eventual blossoming of their romance. Emma later dies on July 15. One Day explores themes of personal growth, the intricate dynamics of relationships, and the nature of life.

One Day was honored as the 2010 Galaxy Book of the Year. Nicholls later adapted the novel into a screenplay—the film, starring Anne Hathaway and Jim Sturgess, was released in August 2011. Additionally, a television series adaptation premiered on Netflix on February 8, 2024.

This guide refers to the 2019 e-book edition of One Day by Hodder & Stoughton.

Content Warning: This guide and source material contain references to alcohol misuse and substance use disorder.

Plot Summary

Narrated from a third-person perspective, switching between Emma and Dexter’s viewpoints, the novel begins on July 15, 1988—St. Swithin’s Day. After four years of college, Emma and Dexter graduate from the University of Edinburgh. They spend the night together in Emma’s bedroom, discussing their aspirations for the future—Emma idealistically dreams of changing the world, while Dexter seeks fame and success. Despite their contrasting personalities, they are drawn to each other.

Each subsequent chapter takes place on a new July 15. Despite their mutual attraction, the two lead separate lives, staying in touch as friends. Emma begins working for a theater cooperative but feels unfulfilled and lost, while Dexter travels the world. They keep in touch through letters and postcards, filled with unspoken desire. Feeling disillusioned with her acting career, Emma takes up a job as a server at a Tex-Mex restaurant in London. Meanwhile, Dexter returns from two years of traveling and finds success as a television presenter. Emma feels trapped in a stagnant life, crushed by the failure of her dreams. In contrast, Dexter is satisfied with his career and has a lavish, glamorous lifestyle, marked by excessive drinking, substance misuse, and sexual experiences.

Emma and Dexter grow closer after a holiday together in Greece; their connection is charged with sexual tension. However, circumstances continue to drive them apart. Eventually, Emma starts a lukewarm relationship with Ian Whitehead, an aspiring comedian. Meanwhile, she decides to rebuild her professional life, obtaining a post-graduate certificate in education and pursuing a career as a teacher.

Dexter, on the other hand, maintains his extravagant lifestyle, sleeping around and engaging in fleeting relationships with TV personalities. Following the death of his mother, his alcohol and substance misuse intensify, leading to the downfall of his career. He and Emma drift apart, only seeing each other occasionally. When, during a restaurant outing, Dexter’s behavior becomes disrespectful, Emma decides to end their friendship.

Realizing she’s settling for a loveless relationship, Emma ends things with her boyfriend, Ian. After a brief affair with her school headmaster, she quits teaching to pursue a career as a novelist. Meanwhile, Dexter falls in love with Sylvie Cope, a sensible, elegant woman, and cleans up his act. Emma and Dexter reconnect at a mutual friend’s wedding and decide to rebuild their friendship, both admitting how much they’ve missed each other. Dexter then reveals he’s marrying Sylvie, who is pregnant, leaving Emma disappointed.

Following his daughter’s birth, Dexter finds himself unprepared for the challenges of fatherhood. Unemployed, he takes a job at his friend Callum’s sandwich chain and resumes drinking. This sparks frequent conflicts with Sylvie, who feels she can’t rely on him. Eventually, Dexter discovers Sylvie is having an affair with Callum, and their subsequent divorce leaves him devastated.

Emma moves to Paris for a few months to write a sequel to her successful debut novel. When Dexter visits her for the weekend, he discovers she is happily dating a French man. Jealous, he finally confesses his feelings to her, prompting a discussion about their relationship. Emma eventually chooses to be with Dexter, and, after years of unspoken desire, they embark on a happy, fulfilling relationship. Emma excels in her writing career, while Dexter opens a successful deli-café. They marry, and Emma expresses a desire for children. However, their unsuccessful attempts at conceiving create tension and strain in their relationship. On July 15, 2004, Emma and Dexter have a house-viewing appointment. While cycling there, Emma dies in an accident.

After Emma’s passing, Dexter feels lost and heartbroken. He resorts to drinking again, getting into fights at bars. Sylvie, his ex-wife, offers comfort, and their bond grows stronger. Dexter also finds solace in his connection with Ian, Emma’s former boyfriend. Over time, Dexter learns to cope with his grief. He starts a new relationship and, three years after Emma’s death, he takes his daughter to Edinburgh, where he and Emma first met. They climb Arthur’s Seat, the hill he and Emma climbed together on July 15, 1988, bringing a flood of memories. Several flashbacks to that day two decades earlier unveil what happened after Chapter 1: The two bonded on their hike, but their time together was cut short when Dexter’s parents unexpectedly arrived to take him to dinner. The novel concludes with them sharing a goodbye kiss, promising to keep in touch.