Barrett Bloom, an eighteen-year-old freshman at the University of Washington, has long anticipated college as a fresh start. Raised on Mercer Island, a Seattle suburb, by her young single mother, Mollie Bloom, Barrett became a social pariah in high school after writing a newspaper article exposing cheating on the school tennis team. The exposé led to the team's disqualification and cost players their scholarships. Her former friend Lucie Lamont, the paper's editor in chief, blamed Barrett for ruining her boyfriend Blaine Walker's prospects. By senior year, Blaine's brother Cole Walker asked Barrett to prom as revenge: after sleeping with her, he and his friends created the hashtag #debloomed and stuffed her locker with flowers daily, turning her last name into a cruel joke.
On the first day of classes, Barrett discovers her assigned roommate is Lucie. In Dr. Sumi Okamoto's Physics 101 class, a reserved student named Miles embarrasses her, and her interview at the campus newspaper, the Washingtonian, falls flat. That evening she attends a fraternity party alone and accidentally sets fire to the building by knocking over a Tiki torch. Lucie identifies her to the crowd, and Barrett flees, sleeping on a common-room couch after Lucie locks her out.
She wakes in her own bed. The date still reads September 21.
Barrett tries to fix her mistakes on the second iteration but botches everything again and accidentally pepper-sprays Miles on the walk to the same party. As she helps him back to Olmsted Hall, their shared dormitory, he references something she never told him in this version of the day. The morning resets a third time. After class, Miles invites Barrett to the Dawg House, UW's student-union building, and reveals he has been stuck in the loop for sixty-one days. He explains that their timelines became misaligned, with different versions of Barrett existing across parallel iterations. Barrett resists his scientific approach, arguing the solution might be personal or magical, as in the movie
Groundhog Day, and storms off to work alone.
Over several days Barrett tries to break the loop through good deeds, but nothing works. By day eight, she reluctantly joins Miles in the physics library. They document their loops on a chalkboard and split their time between Miles's scientific research and Barrett's instinct-driven methods. Barrett tries to reconcile with Lucie, filling their room with balloons and bagels, but Lucie dismisses high school, and the effort backfires.
Barrett and Miles interview Miles's mother, Dr. Okamoto, on a faculty rooftop garden, where a colleague mentions Dr. Ella Devereux, who taught a course called Time Travel for Beginners before leaving UW about a decade earlier. On Day 19, Barrett pays a classmate to search for cached web content about Devereux, which leads them to Elsewhere, Lucie's parents' media company. Barrett convinces Lucie to visit the offices, where Lucie's father remembers Devereux but cannot explain why her articles vanished. During the visit, Barrett learns Lucie's true passion is dance, not journalism, and that her life is constrained by parental expectations. On the drive home, Lucie apologizes for her high school behavior and confides that she is questioning her sexuality.
As the days accumulate, Barrett and Miles grow closer. Miles reveals a secret passion for film and prepares a makeshift Shabbat dinner (the Jewish Sabbath meal), bonding with Barrett over their shared but distinct Jewish upbringings; Miles was raised both Japanese and Jewish. They embrace a "fuck-it list," using the loop for adventures like flying to Disneyland and operating a free ice-cream truck. On Day 21, they pick up Miles's older brother, Max, who is completing his third stint in rehab for addiction. Miles confides that Max's struggles made him rigidly academic, and he dreads leaving the loop because, while stuck, Max is always getting better. Barrett wakes the next morning with phantom pain from a joke tattoo that no longer exists, confirming physical sensations are bleeding across resets.
Barrett takes Miles to Vancouver for his birthday. When Miles gives her a yellow rose, Barrett has a severe panic attack; roses are deeply tied to the post-prom harassment she endured. She tells Miles the full story of prom night. As they nearly kiss, Barrett experiences a fragmented vision of a kiss she does not remember. Miles admits that in an earlier iteration, a different version of Barrett kissed him at a party, and he kept the secret for weeks. They argue on the drive home, and a semitruck strikes their car.
Barrett wakes on September 21 with severe phantom injuries. She ignores Miles for days, spiraling into destructive behavior. She confronts Cole, but he is dismissive. She breaks into the Washingtonian newsroom and discovers physical archives about Devereux and a sticky note bearing the professor's address in Astoria, Oregon. Barrett brings the discovery to Miles; as he bandages her injured arm, she finds she can forgive him. That night, Lucie gives Barrett a long-lost sock found on another floor, and Barrett realizes objects have been crossing between parallel iterations within Olmsted. The building is the connection point.
They drive to Astoria and meet Dr. Devereux, a retired British physicist. She explains the many-worlds interpretation of quantum mechanics, positing infinite parallel universes, and offers her own extension: "connection points" where universes nearly touch may allow crossings. She also suggests time itself may have shifted Barrett and Miles onto the path they were meant to follow. She advises them to go where gravitational pull is strongest at the time of the daily reset.
On the drive home, Barrett detours to Long Beach, Washington. Walking the rainy beach, Miles confesses his feelings, and Barrett reciprocates. They share their first kiss and later sleep together, an experience that contrasts sharply with Barrett's prom night. The next day, they help Jocelyn Thierry, Barrett's mother's girlfriend, propose a day early; Mollie says yes.
On their final September 21, Barrett and Miles descend to Olmsted's subbasement just before the 6:50 a.m. reset. Miles pulls the emergency brake, afraid their memories will be erased and Max might relapse. Barrett tells him she loves him and promises she will love him tomorrow too. She argues that real life, with all its uncertainty, is worth the risk. Miles says he trusts her. They press the subbasement button, and the elevator plunges into darkness.
Barrett wakes at 7:15 a.m. on Thursday, September 22. When she finds Miles in the quad, he does not recognize her. Devastated, Barrett goes home and tells her mother the full truth about high school for the first time. She makes a counseling appointment, finishes a profile of Dr. Devereux, and brings it to the Washingtonian, where editor Annabel Costa offers her a trial assignment.
On Friday, Barrett sits in Miles's usual seat in Physics 101, surrounded by mozzarella sticks, a bagel, and a cookie: foods tied to pivotal moments in their shared history. She brings Miles to the physics library and writes their story on the chalkboard. When a stack of books crashes to the floor, Miles catches one,
A Short History of Nearly Everything, and his memories flood back at once. Barrett holds his hand until the rush subsides.
They embrace and kiss. The librarian, Gladys, interrupts, remarking that it is nice to see them doing something other than arguing. Miles tells Barrett he loves her, and they plan a real date: a showing of
Pride and Prejudice at a downtown theater. Walking through the autumn-changed campus, Miles asks if Barrett meant what she said in the elevator. She confirms she loves him. He replies: "We have all the time in the world" (419).