In Crouch End, London, electronics salesman [Shaun](simon-pegg) is feeling lost and lacks purpose in his life. His colleagues, particularly Noel (played by Rafe Spall), disrespect him, while his relationship with his stepfather Philip (portrayed by Bill Nighy) is strained, with their encounters limited to a mere visit every couple of months. Moreover, his girlfriend [Liz](kate-ashfield) is frustrated with their monotonous routine of visiting the same pub, the Winchester, night after night. Shaun shares Liz's disdain for her friends Dianne (Lucy Davis) and David (Dylan Moran), and the tension in their relationship escalates when Liz ends their romantic involvement after Shaun forgets to book a dinner reservation.
As the day unfolds, news breaks out about a US space probe crashing to Earth, leading to eerie reports of a strange epidemic. Despite this chaos, Shaun remains oblivious to the growing signs of a zombie apocalypse until he and his roommate [Ed](nick-frost) face a couple of zombies in their backyard. Their realization dawns on them that the only way to eliminate these undead threats is by destroying their brains.
Determined, Shaun devises a plan to rescue his mother Barbara (Penelope Wilton) while also hoping to reunite with Liz. However, in the midst of their frantic escape, they run into obstacles, including Shaun's now-zombified housemate, Pete, and a horde of undead rising from their graves. After a series of chaotic events, which include dodging zombies, the group manages to gather together in a tense setting at the Winchester.
Inside the pub, the atmosphere intensifies when Barbara, having been bitten, becomes one of the undead after offering her blessing to Shaun and Liz. Heartbroken, Shaun is forced to make the excruciating choice to shoot his mother. In a gripping climax, the situation escalates as zombies breach the pub's defenses leading to a harrowing fight for survival that claims the lives of several characters.
As a final act of sacrifice, Ed stays behind to fend off the zombies while Shaun and Liz make their escape through a hatch. Ultimately, they find refuge when the Army arrives to quell the undead threat.
Fast forward six months later, life slowly returns to a semblance of normalcy, with surviving zombies now repurposed for labor. Shaun and Liz have moved in together, but there’s a twist — Shaun keeps the zombie Ed tethered in his shed, where they share an odd bond through video games. It’s a bizarre yet heartwarming conclusion to an otherwise frantic tale of love and survival in a world turned upside down by the undead.
