The film begins in the Winchester. A local London pub. Shaun, his girlfriend Liz and her two friends David and Dianne are socializing while Ed plays away on the slot machine. Liz is trying to encourage Shaun to strengthen their relationship and be more adventurous, rather than just reminise in the pub. Liz displays her cynism by reminding how she hasn't even met Shaun's mum yet. This intro scene ends with Shaun staring vacantly towards the camera, clearly displaying anxiety.The movie's intro credits roll, continuinely panning right through scenes of regular people moving supermarket trolleys, working behind tills, waiting at the bus stop, or mindlessly listening to street music, all staring and acting zombie-like (a reference to the satirical elements of Dawn of the Dead). Before finishing at Shaun's flat. Shaun wakes up and joins Ed at the couch to join him on his PlayStation, before he reminds him that he has to go to work. When Shaun is getting ready, his second flat-mate and college buddy Pete confronts him how he's fed up with Ed lounging around, and staying unemployed. Shaun defends him by just saying he's harmless and fun to have around, to which Pete replys "Why? Because he can impersonate an orangutan? Fuck-a-doodle-do!". Both Pete and Shaun leave for their work, with Shaun asking Ed to take down any messages from the answering machine on the phone. Just as Shaun leaves, Liz leaves a message behind to book their restaurant dinner an hour earlier.The next sequence of scenes involve Shaun side-tracked by bizarre events including reports of attacks on tabloid headlines, people collapsing a bus stops, and television reports of more attacks and military dispatchment. At Shaun's work (an electronics retail shop) Shaun's step-dad Philip makes a visit to remind him of his by-monthly visit to his mum, and they are both very cold towards each other. Trying not to lose face to a younger employee who he moaned at for using his mobile phone, he ignores every word from a telephone call from Liz when she tries to remind him of the dinner times. Later, when Shaun is purchasing flowers for his mum, he notices a homeless man outside staggering and trying to eat the pigeons, before vanishing. On his way home, Shaun gets off the bus early as traffic is clogged by more accidents involving people passing out in their cars, to which he bumps into his old flame Yvonne asking how he's getting on with Liz, which instantly triggers his memory, as we cut back to his flat as he desperately tries to call the restaurant to change the times, only to hear their bookings are full. Liz then phones and Shaun explains that he forgot all about it, then suggests maybe they go to the Winchester...Liz then hangs up. Shaun grabs the flowers and makes his way down to her flat where David and Di are as well to make up. Liz launches into a tirade of all the broken promises he's made, and how she's tired of putting up with their relationship that's clearly going nowhere, so she dumps him right there and then.Shaun makes his way to the Winchester through the pouring rain, throwing his mother's flowers in the trash, to reconcile with Ed. They spend the night joking and drinking heavily trying to get over the break-up, when a figure, moaning, batters against the pub window, to which Ed simply retorts 'Piss head!". Drunk and still singing, the duo make their way outside - not noticing the zombie girl tearing someone's head off, and mocking a moaning zombie as another drunk - and make their way back home. They continue to sing and play loud music, until Pete storms downstairs, throws the record out the window and launches into a barrage of swearing for playing music at 4:00 in the morning, verbally attacks Ed and tells Shaun to sort his life out. Ed notices that Pete's hand is bandaged an he tells him that a 'crackhead' bit him and he has a splitting headache. He scathes at them one last time for leaving the front door open, again.The next morning arrives and Shaun decides to down the corner shop for a drink, and a Cornetto for Ed. Still tired from last night, on his way to and back from the shop, Shaun is completely oblivous to the carnage surrounding him. Smashed cars, blood-stained floors/windows, corpses lying on front porches and hoardes of zombies slowly flooding the streets. Back at the flat, Shaun skips through the TV channels, past entertainment channels and news reports of the incidents, when Ed tells Shaun, there's a girl in their garden. Out in the garden, they try and get the girl's attention. When she turns around, they think she's drunk, until she attacks them. Thinking that she's just a nuisance, Shaun pushes her back and she trips and empales on a metal stump, only to stand straight back up again. Shocked, they choose to back inside only to be nearly cornered by another male zombie. Back inside, Shaun dials 999, only for every response to be engaged. The pair sit down on the sofa watching the news, when a zombie with a severed arm makes his way inside (Shaun left the front door open again) the pair attack it by throwing any object they can. Only for Ed to kill it by smashing a glass ash tray on its head. The pair then decide to take on the two in the garden, again, by throwing any household object they can, at their heads. When Ed finds the record Pete threw out last night and throws it at the male zombie, it sticks into him like a blade, prompting their second idea... They go through their record collection and throw every record they dislike (the Batman soundtrack, Dire Straights) and use them as projectiles. When that plan fails, Shaun bashes down the shed door, and the pair arm themselves with a Cricket Bat (Shaun) and a shovel (Ed), they then beat the zombies to death. Back inside, Shaun and Ed are watching the news reports about containing anyone who has been bitten, to which Shaun and Ed then remember Pete. They call him, but get no response. Shaun then tries to call Liz but can't through, only for his mum (Barbara) to call him. Fearing for her safety, she tells him that some men were trying to attack them, but only Philip was bitten, much to Shaun's relief. Shaun and Ed then go through plans to rescue his mum and Liz, kill Philip, and rendevouz at the Winchester. Shaun goes the toilet first, only to discover a naked zombified Pete in the shower. Shaun and Ed no longer waste time and head outside to Pete's car, only to attract the attention of every zombie outside. They drive at high speed, listening to the radio's reports of 'a coming apocalypse' and witnessing zombie attacks on every street corner they drive past. Until they make it to Philip's and Barbara's house.Shaun goes inside while Ed Stays outside on lookout. Barbara greets Shaun warmly and makes him tea while he goes to kill Philip, only to realise he hasn't become a zombie yet. He eventually convinces them to come with them. Outside, Ed has intentionally crashed Pete's car so they ride in Philip's Jaguar, but then, another zombie attacks and bites Philip on the neck; a fatal wound. And the four quickly get in and drive to Liz's. At Liz's flat, Shaun tells Ed to stay outside on lookout again. Zombies are swarming outside, and Shaun dispatches them quickly to get to the front door. When he gets cornered again, he makes his way into the flat by climbing up to the window, a method he tried but failed earlier. Inside, Shaun convinces Liz, David and Di to come with them to head to the Winchester to be safe, and the four make their way outside clubbing the zombies to get to the car. Its here when Shaun 'finally' introduces Liz to his mum. On the way down the road, Ed is intentionally mowing down every zombie he can. Philip, bleeding profusely, tells Shaun his tough attitude towards him was to help him become better and hopefully he would look up to him. He lastly tells Shaun he loves him before he dies. Shaun, in an emotional state, tells Ed to pull over and tells Barbara that Philip is dead, in which she looks and says '..no he isn't..' Shaun then panics as he sees that Philip has instantly become a zombie, and shouts for everyone to get out. Out in the open and vunerabale, the six head for a short-cut, making their way through the back-alleys of the local houses. They then bump into Yvonne and another group of five (who all strike similar resemblance to Shaun's team) who are trying to survive. After some quick talk, Shaun and Yvonne embrace before parting ways. They start to pass through the back gardens. When they come to a garden where the Winchester is just over the other side, Shaun sees that his mum is missing from the team, and Shaun quickly jumps back into the previous garden, where he fends off another zombie. Liza and Di join in to help, passing a tennis pole to use as a weapon, Shaun then impales the zombie against a tree, imobilising it. Although not killing it. Shaun checks over the fence to see if the coast is clear, only to his horror to discover that there are hundreds of the undead swarming the street, so Shaun has an idea: Dianne is a actress-in-training, so she gets the other 5 to mimmick the actions and sounds of the zombie impaled behind them so they can sneak through the crowds unsuspected. This plan pulls off. But when they make it to the doorway, the zombies start to raise suspision, only for Ed to completely give the game away when he answers his mobile phone and starts chatting away. Shaun knocks away the phone and barrates at Ed for his habit of messing up all the time. He ceases when he sees that ALL the zombies have turned their attention to the group. David quickly throws a trash bin through the window for everyone to get inside. To make sure the zombies don't follow, Shaun waves and shouts and gets the zombies to chase him (or simply, stagger after him) so the group can make it inside. Barbara spots the flowers Shaun was going to buy for her through the rubbish and get inside the pub.Hours pass and Shaun has not returned, David suggests blocking up the window, although Liz is insistant that Shaun will return, leading to David complaining about the entire situation they're in. Shaun eventually makes it back (through the back door) saying that he 'gave them the slip'. Night falls, and the group of 6 are bored and decide to see there's anything on the TV. As there's no electricity in the area, Shaun goes into the back to turn on the main circuit. When he turns the lights on, he's shocked to discover the zombies have followed him back. Back in the main pub, the TV channels are broadcasting nothing. Shaun whispers that the zombies followed him back, and they keep very quiet. However, Ed being Ed, messes it up again by playing on the slots and triggering more noise. Zombies now surround the outside of the pub, and the zombie pub landlord crawls in to attack. With the electrcity on, the Juke box turns on and starts to play "Don't Stop Me Now" by Queen. Shaun, Ed and Liz all grab pool cues and (in a classic scene) club the zombie to the song's beat. Dianne joins in by throwing darts at the zombie, only for one to land in Shaun's head. Ed tosses the rifle from the bar to Shaun (who thinks its deactivated) and kills the zombie by smashing its head through the Juke box. Asking why Shaun didn't just shoot him, Shaun tries to explain its not functional only to be blown back when he pulls the trigger.Packed together, the group join to defend against the masses of the undead. As they start to charge through the windows, Shaun fires but misses several times, with none of the other's directions being much help, except when Ed calls out the same way they do in their video-games, Shaun lands a head-shot. Shaun notices something's wrong with Barbara, and quickly comes to her attention. She was bitten by the zombie they impaled with the tennis pole. Every one of the group comes to her need except for David, who's been left with the rifle. Barbara thanks Shaun for the flowers, then collapses dead in his arms. David cocks the gun and aims for Barbara, and Shaun explodes in a fit of rage, holds a broken bottle to his neck and threatens him to stop aiming at her. Ed does the same, Dianne says this ain't fair, so he gives her the broken bottle (to point at Shaun) and Ed points a corkscrew at David, leading to a mexican stand-off, which ends just as quickly when Barbara rises as a zombie. Shaun takes the gun, says sorry to his mum, and shoots her dead. When David says he did the right thing, Shaun retaliates by punching him. David tries to shoot Shaun, only for the gun to run out of shells. He then decides to leave. When Dianne barrates at him, he relents and says he sorry, but Dianne says he should apologize to Shaun. When he tries, zombies smash through the window and pull David through, completely dismembering him. Dianne irrationally opens the front door and charges for the zombies in a blind effort to save David. Her fate is left unknown. The zombies break into the pub at all corners, including Pete, much to everyone's suprise. Pete and others swarm over Ed and bite into him, and Shaun shoots Pete in the head finishing him off. Shaun and Liz then jump over the bar, setting the bar table on fire with the spirits. Ed, severely wounded makes it over the bar to join them. With the rifle shells left in the burning mess, they only have two shells to spare and make their way into the cellar, as there is a lift down there that will lead to the outdoors. With the lift and the trapdoor not working, the remaining three are trapped. Shaun contemplates the last two shells for Liz and himself. Ed says 'I don't mind being eaten'. They share a last cigarette between them, only to see the power switch for the lift when they light up. Shaun tries to get Ed to come with him, but Ed knows he's done for anyway as he's bitten, and decides to stay. Liz and Shaun say their farewell to Ed and make it out into the street. Prepared for more fighting, luck comes their way as the military arrives and opens fire on the zombies. Accompanying them is Yvonne, who says they're evacuating any survivors. Shaun and Liz follow, holding hands.The next scene opens with several TV shows and reports saying that months have passed since the outbreak, and that zombies have now been used in everyday life. For menial jobs, such as trolley stacking and used as part of silly game shows. Shaun wakes up - in the same zombie-like way at the beginning of the film - and is sharing the flat with Liz, who have become a couple again. The film ends with Shaun saying he's gonna pop out to the shed, where the zombie Ed is chained up so he can play video-games with.