In 1989, scientist Hank Pym resigns from S.H.I.E.L.D. after discovering their attempt to replicate his Ant-Man shrinking technology. Believing the technology is dangerous, Pym vows to hide it as long as he lives. In the present day, Pym's estranged daughter, Hope van Dyne, and former protégé, Darren Cross, have forced him out of his own company. Cross is close to perfecting a shrinking suit of his own, the Yellowjacket, which horrifies Pym.
Former teen salsa champion Bruce Garrett (Nick Frost) is now an engineer. Bruce gave up dancing after he was brutally bullied by older boys. When he finds out that his new boss, Julia, (Rashida Jones) is passionate about salsa dancing, he decides that the only way he can win her over is by re-mastering the art of dance. He seeks out his old teacher Ron (Ian McShane), who forces him to confront the reasons he quit dancing in the first place. He struggles with low self-esteem, as well as a bullying coworker and rival, Drew (Chris O'Dowd), who constantly dominates the attention of their boss Julia who they're both interested in seducing. With the help of his salsa classmates, teacher, and his former dancing partner, his sister Sam (Olivia Colman), Bruce gets up the courage to relearn all his 'rusty' dance steps and to recapture his lost "corazón" (heart), not only for the dance but for his life. When ready, his friends convince him to enter the local nightclub's salsa dance competition, with the idea that he'll invite Julia to be his dance partner. But when he goes round to hers to ask her out to the dance, he is tricked into believing that he's interrupting an intimate evening she's spending with Drew, so leaves before asking, disillusioned. Julia, meanwhile, discovers what Drew is up to and outright rejects his advances, then kicks him out whilst threatening his position at work. Julia follows Bruce to the nightclub, where he's been doing quite well with his old partner (his sister) and an old routine, and is about to enter the final heat/round of the competition. When he notices Julia had followed him to the club, he's elated and finally plucks up the courage to ask her to dance. They dance the last round of the competition, where Bruce goes on to lose the competition, but regains his true self and finally wins the girl.
Gary King (Simon Pegg), a middle-aged alcoholic, tracks down his estranged schoolfriends and persuades them to complete "the Golden Mile", a pub crawl encompassing the 12 pubs of their hometown of Newton Haven. The group attempted the crawl as teenagers, but failed to reach the final pub, The World's End.
After dating for just two weeks, Tom (Iain De Caestecker) invites Lucy (Alice Englert) to go with him and some friends to a festival. The night before, Tom plans to take Lucy to the Kilairney House Hotel, which he booked online and is hidden away on a series of remote roads in the Irish countryside. Before making their way to the hotel, the couple stop at a pub and a confrontation occurs between Tom and some of the locals.
Chris (Steve Oram) is a caravan fan and aspiring writer who takes his girlfriend Tina (Alice Lowe) on a road trip, much to the chagrin of Tina's mother (Eileen Davies), who has never forgiven Tina for the death of their dog "Poppy". At their first stop, a tramway museum (filmed at Crich Tramway Village, the home of the National Tramway Museum), Chris confronts a man (Tony Way) who is littering, and the man refuses to pick up his rubbish. When they get back to their car, Chris runs him over and kills him, which upsets the couple but they continue onward on their trip. Chris claims that the death was an accident, but his smirk—visible to the camera but not to Tina—in the immediate aftermath makes it clear it was deliberate.
Graeme Willy (Simon Pegg) and Clive Gollings (Nick Frost) are British comic book enthusiasts and best friends who travel to the United States to attend the annual San Diego Comic-Con International, and to take a road trip through the American Southwest to visit sites significant to UFO lore. While driving on a remote desert highway at night, Graeme and Clive observe a car driving erratically and then crash. They stop to investigate and offer assistance to the driver, who turns out to be an alien named Paul (voiced by Seth Rogen). Clive faints, but Graeme agrees to assist Paul and gives him a ride.
Walking home on Bonfire Night through "The Ends" in Brixton, new-to-the-area nurse Samantha Adams is mugged by a small gang of teenage hoodlums: Pest, Dennis, Jerome, Biggz, and leader Moses. The attack is interrupted when a meteorite falls from the sky into a nearby car, giving Samantha the chance to escape. As Moses searches the wreck of the car for valuables, his face is scratched by a pale, hairless, eyeless dog-sized creature; the object which fell from the sky was its cocoon. The creature runs away, but the gang chase and kill it. Hoping to gain fame and fortune, they take the corpse to their acquaintance, cannabis dealer Ron, to get advice on what to do. He lives at the top of their tower block, Wyndham Tower.
In Toronto, 22-year-old Scott Pilgrim, bass guitarist of floundering garage band Sex Bob-omb, is dating high schooler Knives Chau, to the disapproval of his friends. Scott meets an American Amazon.com delivery girl, Ramona Flowers, having first seen her in a dream, and loses interest in Knives. As Sex Bob-omb plays in a battle of the bands sponsored by one "G-Man Graves," Scott is attacked by Ramona's ex-boyfriend Matthew Patel. Scott defeats Patel and learns that, in order to date Ramona, he must defeat the remaining six evil exes. He had previously been made aware of this in an email that he received from Patel, warning him of the attack, but dismissed it as "boring.
Police Constable Nicholas Angel, a high-achieving member of the Metropolitan Police Service, is promoted to Sergeant but it comes with being transferred to the village of Sandford, Gloucestershire, for being too good at his job while making his colleagues look bad by comparison due to his skills. Angel finds the town is generally devoid of any crime, with its local Neighbourhood Watch Alliance (NWA) helping to keep the peace as everyone prepares for the "Village of the Year" award contest. Angel finds minor instances of disorderly conduct, during which he confiscates a shed full of unlicensed fire arms including a naval mine, pursues an escaped swan, and arrests a drunk driver who turns out to be his new partner PC Danny Butterman, the son of town chief Inspector, Frank Butterman.
Shaun (Simon Pegg) is a 29-year-old electronics shop salesman with no direction in life. His younger colleagues show him no respect, he has a strained relationship with his stepfather, Phillip (Bill Nighy), and a tense one with his housemate Pete (Peter Serafinowicz) because of Ed (Nick Frost), Shaun's other housemate and vulgar, unemployed best friend. Furthermore, Shaun's girlfriend Liz (Kate Ashfield) dislikes their social life as they spend every date at the Winchester, Shaun and Ed's favourite pub. Because Shaun always brings Ed, Liz is always forced to bring her flatmates, David (Dylan Moran) and Dianne (Lucy Davis). After a bad day at work, Shaun forgets to book a table at a nice restaurant, and after suggesting the Winchester again Liz breaks up with him. Shaun drowns his sorrows with Ed at the Winchester. While celebrating at home, an enraged Pete — suffering from a bite wound caused by "some crackheads" — confronts Shaun on his flaws, telling him to sort his life out.