A struggling musician realizes he’s the only person on Earth who can remember The Beatles after waking up in an alternate timeline where they never existed.
After the worldwide power outage, Jack (Himesh Patel) becomes a worldwide instant phenomenon performing the songs of the unknown Beatles, but is wracked with guilt over the deception and having not recognized his love for Ellie (Lily James).
On the day of the release of his album, he meets two others who can also remember the Fab Four. He expects them to be angry with him for taking credit for the songs, but they are actually grateful that the Beatles’ music is returning to the world, in any form. They give him a slip of paper with an address, and Jack visits a 78-year-old John Lennon (uncredited) who has had a happy life as a sailor, settled with the love of his life, but lost her to cancer.
Jack returns to London, and asks a favor of Ed Sheehan (himself). He goes on stage at the end of Sheeran’s concert at Wembley stadium, performs several songs, and then confesses that he didn’t write any of them. He credits John, Paul, George, and Ringo, and announces that all of the songs will be released for free. He also begs Ellie’s forgiveness, and she takes him back.
In a final montage to the tune of “Ob-La-Di, Ob-La-Da,” we see Jack and Ellie (both teachers) happily settled, with two kids.
Jack Malik is a struggling musician. After a worldwide blackout that causes him to get into an accident, he wakes up to find that he is the only person in the world who remembers The Beatles and their songs. After playing “Yesterday” for his friends and seeing their amazed reactions, he starts to write down all the Beatles songs he remembers.
Jack gets the attention of a music producer, and then Ed Sheeran, and then Ed’s cutthroat manager Debra Hammer. He becomes a major music sensation, but is still troubled by his guilt over plagiarizing music that isn’t his. Furthermore, it puts a strain on his friendship with his best friend Ellie Appleton, who has been in love with Jack since they were kids.
Jack is met by two strangers, Leo and Liz, who heard Jack perform the songs. They also remember The Beatles, but instead of calling him a thief, they thank him for keeping their music alive. Liz even helps Jack locate John Lennon, who is still alive in this world. Without fame, he spent a long and happy life with his family, and he felt fulfilled. This inspires Jack to come clean to an audience at Wembley about how he is a fraud, but he has his friend Rocky upload all the Beatles songs online for free, which infuriates Debra. He runs away with Ellie after telling everyone how he loves her.
Jack and Ellie later get married and have two kids. He teaches Beatles songs to children now. The world doesn’t exactly go back to normal, and Jack is no longer a superstar, but he is happier than he’s ever been.
In the English county of Suffolk, Jack Malik (Himesh Patel) is playing a gig with one of the songs he wrote. He has been aspiring to reach musical success for a while now, with very little luck. Jack also works a part-time job at a superstore, but for him, it’s a dead end. His manager and best friend, Ellie Appleton (Lily James), books him a gig at a music festival in a tent.
The gig ends up being in a small tent, with very few people actually paying any mind to Jack’s music, other than Ellie and their friends Nick (Harry Michell), Carol (Sophia Di Martino), and Lucy (Ellise Chappell). There, he finds his bumbling friend Rocky (Joel Fry) there working, but he is high as hell. It gets to the point where Rocky screws up too much and gets fired. Jack expresses his disappointment over his failures to Ellie, thinking that if he hasn’t reached the big time now, then he never will. He goes home later that night on his bike, when all of a sudden, the entire planet experiences a blackout. In the darkness, a bus hits Jack, sending him flying and hitting the pavement.
Jack wakes up in the hospital to find Ellie next to him. He is okay, but his two front teeth have been knocked out. Ellie later takes Jack to Nick and Carol’s home, where Rocky is staying for the time being. Ellie gifts Jack with a new guitar since his other one got wrecked in the accident. He starts to play the song “Yesterday”. Everyone thinks it’s beautiful and that he wrote it, but he says it was written by Paul McCartney. The only answer he gets is, “Who?” Jack insists that The Beatles wrote the song and that it’s one of the greatest songs ever written, but they just assume he’s being cocky. Afterward, Ellie drives Jack home, but he opts to take a bus ride home, as he is very confused. He goes home and looks The Beatles up on Google, but only gets results for the insect. Nothing even comes up on the John, Paul, George, and Ringo. Jack looks through his record collection and doesn’t find a single Beatles album. He also discovers that, for some reason, the band Oasis doesn’t exist either (and, as he later finds out, neither does Coca-Cola, cigarettes, and Harry Potter). He runs to Ellie’s home in the pouring rain to ask if she really doesn’t know who The Beatles are.
Jack finds himself in a conundrum, as he remembers all the Beatles songs, but worries that he would be doing something wrong by making it sound like he wrote them. Nevertheless, he makes notes and columns on every song of his that he knows all the lyrics to. He starts to write them down, with the hopes of having others hear it. He attempts to play “Let It Be” for his parents Jed (Sanjeev Bhaskar) and Sheila (Meera Syal), but Jack keeps getting interrupted when their annoying friend Terry (Karl Theobald) comes over and makes unsubtle quips about Jack’s musical failures.
After several unsuccessful shows, Jack gets the attention of a recording producer named Gavin (Alexander Arnold), who loves what he’s heard. He invites Jack and Ellie to record some songs. Jack performs “I Want To Hold Your Hand” with Ellie singing backup. He then records a few more songs, which start to get radio play. This gets the attention of none other than Ed Sheeran. He calls Jack, but he assumes it’s a prank. Ed then shows up to the Malik house and personally speaks to Jack about being his opening act when he tours around the States. Jack is honored and he accepts. His friends later throw a party for him, but the mood is dampened when Ellie is in his room and sees she’s featured on the column of “good chums” and not the column of love songs. Jack realizes Ellie admitted she’s in love with him, but he tries his best to avoid discussing it any further by returning to the party.
Jack joins Ed on their tour, accompanied by Rocky as a roadie. During one show in Moscow, a man, Leo (Justin Edwards), listens to Jack’s music and has a bewildered look on his face before he goes home to look up Jack’s album to see the songs he has.
Jack and Ed spend a lot of time together, and Ed even challenges him to create a new song to play to an audience. Ed does his, and Jack sings “The Long and Winding Road”. Ed admits that Jack is way better than he is, although Jack doesn’t want to take that credit. After playing a couple more Beatles songs, Jack is approached by Ed’s manager, Debra Hammer (Kate McKinnon). She offers to sign Jack to her label, but is super blunt about how the label will acquire most of the money he makes, and also how Jack REALLY needs to change his doughy, unkempt appearance if he wants to maintain some kind of image.
Jack’s star rises quickly after signing under Debra. He and Rocky get chased through the streets by rabid fans, and his music becomes a worldwide phenomenon. However, Jack continues to feel pressure to put out as much Beatles material as he can. He even dreams that he is on James Corden’s show and is confronted by Paul McCartney and Ringo Starr over his plagiarism. He tries to record one of his own personal songs, “Summer Song” (a favorite among his friends), but Debra hates it.
During a meeting with his marketing team, the head of the team (Lamorne Morris) addresses the titles of Jack’s albums (Sgt Pepper’s Lonely Hearts Club Band and The White Album), since they are confusing to their audience, so they decide to call it “The One and Only”, implying that only Jack is responsible for the songs, which just makes him feel more guilty.
Jack can’t remember the lyrics to “Eleanor Rigby”, “Penny Lane”, and “Strawberry Fields Forever”, so he and Rocky travel to Liverpool for inspiration by visiting the sites that the songs are named after. A woman named Liz (Sarah Lancashire) spots the two at the sites and watches them suspiciously.
While in England, Jack is visited by Ellie. The two later go to his room and start to kiss, but Ellie feels awkward about it since they are giving in to their mutual feelings at the height of Jack’s newfound success. The next day, he tries to catch her as she heads back, right before he and Rocky need to return to L.A., and he finds her in a train station restaurant. Although Jack tries to talk to her, Ellie says that she has waited for too long for Jack to love her back. He joins Rocky on the trip back.
Jack returns to keep performing. He later receives a call from Ellie, saying she has started seeing Gavin, and she wanted to let him know before he found out from someone else. She and Gavin, plus her and Jack’s friends, all show up at a huge beach show to see him play “Help!”, although Ellie sees that he’s not just singing it. Later, Rocky tells Jack that he has two visitors. It’s Leo and Liz. It turns out they are the only other two people besides Jack who still remember The Beatles, but since they can’t sing, they are thankful for keeping their music alive. Although they have a few criticisms, in particular, Jack forgetting some lyrics and also turning “Hey Jude” into “Hey Dude” (that’s Ed and Debra’s fault), they all agree that a world without The Beatles is worse off. Liz also helps Jack with one other thing.
Jack takes an address from Liz and directed to the home of none other than the still-living John Lennon (Robert Carlyle). Since he is not a musician in this world, he has been able to live to 78 and had spent a lovely life with his wife and children. Jack asks if he wished things turned out differently, but John assures him that he had everything he needed, and that was enough for him. Jack asks to hug John, and although he thinks he’s a weirdo, he allows it.
At Wembley, Jack performs another show, but he gets help from Ed and Rocky. He has them bring Ellie backstage at the end of the show, and they put the camera on her. In front of the whole audience, as well as Debra, Jack not only confesses his feelings for Ellie (which she hears), but also that the songs were written by The Beatles. He no longer wants to take credit for the songs or receive any money for it, so he has Rocky upload all of the songs online for free. He leaves the stage to go meet with Ellie, who is stunned by what she heard. Gavin also heard it, but he isn’t mad since he knew he wasn’t going to match up to Jack (but he later ends up with Lucy). Fans, plus an enraged Debra, chase after Jack, but he flees with Ellie while Rocky holds everyone back. Jack and Ellie go home and make love for the first time.
Later on, Jack is seen at a school teaching kids other Beatles songs, and they sing “Ob-La-Di, Ob-La-Da”. It is played over a montage of Jack and Ellie getting married and having a son and daughter. Even with his fame gone, Jack has found a greater success in his personal life.