Stephanie Perkins's novel centers on Isla Martin, a shy redhead, and Joshua Wasserstein, an aspiring cartoonist, both seniors at the School of America in Paris (SOAP), an elite American boarding school.
Late one summer night in Manhattan, Isla stumbles into a café called Kismet while loopy on Vicodin after wisdom-teeth surgery. She spots Josh, her longtime crush, sketching at a table. The painkillers dissolve her usual shyness, and they talk freely for the first time. Josh draws her portrait, pays for her meal, and walks her home through a rainstorm. The next morning, Isla remembers almost nothing and is mortified. She returns to the café repeatedly, but Josh never reappears. She later learns the Wasserstein family left for Washington, DC, two days after their meeting.
When senior year begins, Isla discovers she has been assigned Josh's former dorm room, its lock still broken. Nate, the Résidence Director, announces strict new rules: Opposite-sex visitors must keep doors open, and overnight stays are forbidden, with consequences up to expulsion. These rules threaten Isla's arrangement with her lifelong best friend, Kurt Donald Cobain Bacon, a boy with autism who regularly sleeps in her room.
An electric tension builds between Isla and Josh during the first week of classes. Isla invites him to sit with her and Kurt at lunch, but Josh catches Kurt's uncomfortable expression and retreats. Isla suspects Josh is put off by Kurt's social differences, triggering painful memories of her only prior boyfriend, Sébastien, whom she dumped for being cruel to Kurt.
Days later, Josh invites Isla to a nearby comics shop. He reveals he is writing a graphic memoir called
Boarding School Boy about his time at SOAP and plans to attend the Center for Cartoon Studies in Vermont. He asks thoughtful questions about Kurt's autism. At the shop, Josh asks about Isla's "boyfriend," revealing he has believed since freshman year that Isla and Kurt are a couple. When Isla clarifies they are strictly friends, both realize their mutual attraction has been blocked by this misunderstanding for three years.
The following weekend, Josh returns from a solo trip to Munich and confesses his feelings. Isla asks him out. Their first date falls on Nuit Blanche, an annual all-night arts festival. They crash a champagne party at the Centre Pompidou, share their first kiss on an escalator during a fireworks display, and end the night at the Treehouse, a secret rooftop balcony above Isla's aunt's apartment. Josh reveals he returned to Kismet after their summer encounter but saw Kurt and assumed Isla was taken. They kiss under the stars.
Their relationship deepens quickly. Josh befriends Kurt and paints a mural inside the Treehouse layering the skylines of Paris and New York. On his 18th birthday, they draw on each other's skin with ink, and Josh tells Isla he is in love with her. She says it back. Kurt accidentally walks in through the broken door, and Nate warns Isla that one more violation will mean a report to the head of school.
Before Josh flies home for his father's Senate reelection campaign, he proposes a secret overnight trip. Isla chooses Barcelona, drawn by the architecture of Antoni Gaudí. They explore the city's landmarks and sleep together for the first time. The next morning, Isla turns on her phone to find 29 missed messages. Isla's younger sister, Hattie, had come looking for her; Nate questioned Kurt, who is unable to lie and revealed their destination. They return to Paris, where Josh's mother has flown in, furious. The head of school expels Josh. They pack his room. Josh inks L-O-V-E onto Isla's fingers before climbing into his mother's car.
Isla receives one month of detention. Josh's parents confiscate his phone and internet access, leaving only handwritten letters and rare calls. Josh sends Isla the complete manuscript of
Boarding School Boy, the first time he has shared the entire work with anyone.
Isla reads it overnight and is consumed by jealousy. The memoir devotes pages to Josh's ex-girlfriend, Rashmi Devi, drawn like a goddess, while Isla's own presence amounts to only eight rough, unfinished pages. When Josh calls from the White House on Thanksgiving, she lashes out. He insists he included everything for honesty's sake, and the conversation leaves both of them wounded.
At a black-tie Christmas party at the Metropolitan Museum of Art, Josh introduces Isla to his parents, who are polite but guarded. He sneaks her into a closed gallery beside the Temple of Dendur and gives her a drawing of a tiny island with a Joshua tree sheltering two entwined figures. In the car ride home, Isla's insecurities erupt. She tells Josh she believes she is a "placeholder" in his life, someone he turned to out of loneliness after his friends graduated. She breaks up with him.
Josh calls dozens of times. Isla does not answer. On New Year's Eve, she races to Kismet at midnight, but Josh is not there. She later learns he received her messages but chose not to come, wanting her to feel the pain she caused him. The calls stop entirely.
In the months that follow, Isla grows. Kurt befriends two sophomores, and Isla recognizes that she, not Kurt, has been the reason they never had other friends. Sanjita Devi, Rashmi's sister, tells Isla that Josh was "consumed" by her and never looked at Rashmi the same way. A letter arrives from Dartmouth College: Isla has been accepted.
Isla gives Hattie the key to the Treehouse as a gesture of trust. On the rooftop in the first snowfall of the year, Hattie asks why Isla believes Josh did not love her. Isla admits she did not think she was worth loving. Then her phone rings. Josh calls because Hattie secretly mailed him a book Isla personalized at a comics festival, with a note saying Isla still loved him. Josh is in Paris with his old SOAP friends, on their way to the Winter Olympics, and wants Isla to meet them.
At the restaurant, Isla watches Josh's friend St. Clair propose to his girlfriend, Anna, at Point Zéro, the bronze star marking the center of France. Afterward, Josh walks Isla home and hands her a revised manuscript, now titled
Spaces. He has restructured the memoir to open with Isla, continuing through his depression after their breakup, his parents' ultimatum to finish the book, and his decision to take the GED, a high-school equivalency exam. The final penciled pages depict him waiting outside her window in the snow.
At two in the morning, Isla looks out her window. Josh is there, shivering on the corner. She runs outside, and they embrace. She brings him inside, and they spend the night together. In the morning, they confirm the plan: Isla will attend Dartmouth, and Josh will join her in New England in the fall. Kurt visits and embraces Josh, telling him Isla is better when they are dating.
The novel's final chapter jumps to June. Isla walks into Kismet at midnight and finds Josh drawing the last page of his memoir, a picture of this very moment. She asks what comes next. He pulls her into his arms and answers: "The best part. The happily ever after."