Andy and Jen, a couple who had been together for three years, have recently broken up. Andy is struggling to cope with the separation and has moved back in with his mother, while Jen stays with her sister Miranda, who has a strong aversion to men. Their breakup has left Andy in a state of despair, and he constantly reflects on the relationship they once shared.
Their love story began in 2015 when they met at a birthday party for Jane, who was Avi’s girlfriend and Andy’s best friend. At the party, they engaged in a deep conversation about their careers, with Andy being a comedian and Jen working in maritime insurance. Their connection was immediate, and they spent the night flirting and talking. As dawn approached, Andy took the same bus as Jen, even though they lived on opposite sides of London. They shared their first kiss on Jen’s doorstep, marking the beginning of their love story.
In the present day, Andy attempts various strategies to move on from the breakup. He starts by buying all of Jen’s perfume from Boots and goes for a ride on Regent’s Canal, but the memories of their relationship continue to haunt him. Andy then resorts to day drinking, ordering a breakfast and a Guinness at a pub as early as 10 am. He decides to reach out to Jane and Avi, asking if he can stay with them for a while instead of living with his mother. However, his heavy drinking leads him to reminisce about his first girlfriend, Nicky, whom he hadn’t contacted in 17 years.
Nicky is surprised by Andy’s sudden contact but empathizes with his nostalgia. The following day, Andy collects his belongings from his former flat with Jen and places them in storage. He moves in with Avi and Jane, immersing himself in their family life and performing his first live comedy gig after the breakup. Avi arranges a boys’ night out to help Andy get over Jen, but Jane’s announcement that she plans to meet Jen for a forest spa retreat nearly derails the plan. The boys indulge in heavy drinking and recreational drug use, leading to a hazy and regrettable night. When Andy wakes up in Avi’s clothes and bed, both men reflect on their actions with a sense of shame.
After another comedy performance, Andy gets involved in two significant events. He initiates Instagram DMs with a young woman named Tash, and he meets Bob, who offers to rent his canal boat in Hackney. However, his living situation on the narrow canal boat becomes less than ideal, and his interaction with Tash takes an unexpected turn when she deletes her account. Andy’s discomfort on the boat prompts him to return to Avi and Jane’s home, while Jane reveals that she is pregnant with their third child.
Andy embarks on a strange friendship with Morris, a 78-year-old Brexit supporter, whose unusual habits and beliefs puzzle Andy. He shares his experiences with Avi and his friends over beers, contemplating the reasons behind his breakdown and odd living situations. Andy attempts to improve his physical health by hiring a personal trainer and eating healthier, but he falls into a cycle of night-time binging and sending sentimental birthday messages to Jen.
One night, after a comedy gig, Andy encounters Morris, who is freezing potatoes and stockpiling canned food, predicting a disastrous year in 2020. A heated argument with Jen at a local bank about closing their joint account leaves Andy even more disheartened. Shortly afterward, his friend Emery achieves great success with his comedy performances in Scotland.
As summer comes to an end, Andy encounters another ex-girlfriend, Daisy, and leaves her a drunken voicemail. He also sees Jen with her new boyfriend, Seb, at a coffee shop, intensifying his obsession with her. By October, Andy shares a kiss with Sophie, a 23-year-old woman he meets after a gig with Emery. They start dating, but their relationship faces challenges as Andy seeks commitment while Sophie remains non-monogamous.
Andy’s comedy career takes a nosedive when he bombs a performance so badly that a viral review claims he “killed all of comedy.” He spirals into depression, pushing Sophie away. By November, he ends his relationship with her. Andy eventually attends Avi and Jane’s son’s birthday party, rekindling his connection with Jen. He has undergone a physical transformation, but their reunion isn’t about getting back together. They realize that their relationship was a “lost weekend,” a period of fun and exploration, and it is now over for good.
Andy takes a break at his mother’s place before writing two letters. One is to his friend Jon, who has recently become single, sharing the lessons he has learned during his five-month journey. The other is a letter to Jen, not intended to be sent, where Andy pours out his feelings. The story skips ahead to New Year’s Eve 2020, where Andy hosts a radio show about his breakup, breakdown, and path to recovery. Jen is in the audience, reflecting on her own experiences and choices.
Jen’s journey is explored, delving into her childhood and her complex relationship with monogamy. Her twenties were characterized by freedom and friendships, but as she approached thirty, societal pressure began to weigh on her. Her relationship with Andy was an attempt to conform to expectations, but doubts about various aspects of her life led her to end it. She goes on a journey of self-discovery, leaving her job and booking a one-way flight to Cartagena.
In January, Andy seeks Jen’s permission to include their breakup in his comedy show, triggering a sense of responsibility for his happiness. She eventually agrees to attend his show, enjoying his performance and reflecting on her own path towards independence. Jen embraces her newfound freedom and independence, venturing into an uncertain future.
The story ends with both Andy and Jen finding closure and moving forward on their separate paths.