Jack Malik, portrayed by Himesh Patel, is a struggling singer-songwriter based in Lowestoft. His unwavering childhood friend and manager, Ellie Appleton, continuously motivates him to pursue his musical aspirations despite numerous challenges. Everything changes dramatically when Jack is struck by a bus during a global blackout. Upon recovering, he performs "Yesterday" for his friends only to discover that they are utterly unfamiliar with the Beatles. In a bewildering twist of fate, he learns that the world has forgotten the legendary band, and with no online trace of their existence, he seizes the moment to present their timeless songs as his own.
Encouraged by Ellie, Jack records a demo with local music producer Gavin. This leads to a breakthrough when pop sensation Ed Sheeran invites him to be his opening act in Moscow. Although Ellie declines to accompany Jack due to her teaching commitments, his roadie friend Rocky joins him instead. Following a memorable performance during which Jack impressively outshines Sheeran in a songwriting challenge with his rendition of "The Long and Winding Road," his career begins to flourish. However, this newfound fame is orchestrated by Sheeran's relentless agent Debra Hammer, who ensures Jack's rise to stardom in Los Angeles.
Amidst this whirlwind of success, there are amusing moments highlighting the absence of famous cultural icons such as Coca-Cola and Harry Potter, which would have made Jack a billionaire several times over. During Jack's farewell party, Ellie finally reveals her deep-seated feelings for him, exposing a complicated thread in their relationship. Despite her absence, Jack moves to Los Angeles to record his debut album, but inspiration eludes him.
In a bid to recollect the essence of the Beatles, Jack journeys to Liverpool, visiting iconic spots like Strawberry Field, Penny Lane, and "Eleanor Rigby's grave." Ellie surprises him by joining him on this adventure, leading to an unforgettable drunken evening filled with passion, yet she firmly expresses her desire to avoid a fleeting romance. When they part ways at the train station, Ellie commendably tells Jack she cannot join him in his glamorous life, leaving him heartbroken.
As preparations for Jack's album launch intensify, tensions rise within the record label when they dismiss his suggested titles taken from the Beatles catalog, branding his work as "One Man Only." Nevertheless, Jack convinces them to host an exclusive rooftop concert in Gorleston to promote it. An unexpected encounter with fans backstage reveals their awareness of Jack's song theft, yet they thank him, cherishing a return to music they thought lost. They provide him the location of the reclusive John Lennon, who, against all odds, has lived quietly into old age.
In a profound conversation, Lennon advises Jack about living truthfully and pursuing true love. Taking this to heart, Jack performs at Wembley Stadium, bravely confessing to the audience about his plagiarism, and reveals his love for Ellie. To reclaim his artistic integrity, he opts to give away his music for free online, sabotaging his record release plans. Ultimately, Jack and Ellie marry, start a family, and he redirects his passion into teaching music, living a life filled with love and authenticity.
