Dead Set

Another runner, Sophie, travels to the studio with Pippa's mother and their driver, who was bitten by a zombie earlier. They reach the studio as he dies and reanimates, killing both women and biting a security guard. As Pippa's eviction is announced, the guard stumbles into the crowd of fans, dies and reanimates and begins to infect others. The zombies invade the studio's interiors and attack Davina, the production crew, and the former contestants. Zombie Danny kills Chloe but Kelly manages to barricade herself in an office. Patrick hides in a toilet cubicle, after sacrificing his assistant and a disabled man to save himself.

In the morning, the housemates are bickering, oblivious to the situation and wondering why Big Brother seems to be ignoring them. Patrick finds Pippa hiding in the green room when he ducks inside to escape zombie Davina. Kelly kills zombie Danny and is then chased outside and attempts to escape in a van. She gets the keys but is forced back inside the closed studio, where she escapes from a zombie cameraman, lurking in the camera runs, by going into the house. The housemates believe that she is a new contestant and she tries to explain that something is behind the two-way mirrors. Marky opens a door to taunt her and the cameraman bursts into the house, biting Angel before Kelly smashes his head in with a fire extinguisher.

Patrick and Pippa are stuck in the green room with no means of communication; their already poor relationship deteriorates rapidly. Meanwhile, Davina continues to prowl the corridor outside, making occasional attempts to get in.

The housemates move Angel to the greenhouse in the garden so that she is contained if she turns. Grayson, a nurse, explains that he needs proper medical supplies to help her. Kelly, Marky, and Space plan to use the van outside to fetch supplies from the nearby supermarket. Kelly tells Grayson to stab Angel in the head if she dies. Veronica and Joplin create a diversion, buying the others time to get to the van that Kelly has the keys for. Former production assistant Claire and other zombies chase them, but they make it just in time. Marky injures his arm on a tool in the back of the van while leaping in.

Grayson tries to comfort Angel, but when she stops breathing he hesitates to stab her and she attacks. Veronica and Joplin, hearing the screams, run to the garden. Grayson stumbles out of the greenhouse clutching his neck, and Angel chases after Veronica. Joplin hesitates inside, watching as Angel tries to bite Veronica. Grayson pushes zombie Angel into the pool just before he dies and then reanimates. Joplin and Veronica trap zombie Grayson with a bed cover and Veronica stabs him in the head just as Kelly, Marky, and Space arrive. Seeing that Angel is unable to get out of the pool, they come to the conclusion that zombies have little intelligence, and Kelly declares that the living will win the day because they can still reason. She kills zombie Angel with a shot to the head from the policeman's gun.

At the country house, Riq turns on the television, and discovers the Big Brother live feed is still broadcasting on E4. Alex hears a French radio broadcast say that a rescue boat has just left, stranding them and any other survivors. Suddenly, Riq sees Kelly and the others on screen.

Riq decides he must get to Kelly, and convinces Alex to leave the safety of the country house and make their way to the studio by boat along the river. Alex is bitten by a zombie while opening a lock gate. Knowing that she will turn, Alex hands Riq her axe and he kills her with it.

Patrick and Pippa manage to kill zombie Davina and make it to the studio control room. Using the PA System they are able to communicate with the housemates and eventually join them in the Big Brother house. Patrick wants to leave the safety of the house and head for the coast, but Kelly shows him the crowd of zombies at the gates preventing them from leaving the compound. Patrick suggests that they cut up Grayson's body to use as bait to distract the zombies while they escape in the van. The housemates disagree but he starts to chop up the body.

Riq makes it to the studio and approaches the Big Brother house. Marky is on the roof, picking off the zombies inside the compound with the policeman's assault rifle. Marky spots Riq and, thinking he is a zombie, aims at Riq and pulls the trigger.

Marky misses shooting Riq several times before Kelly recognizes him and stops Marky from shooting. Once inside, Riq warns that Patrick's plan won't work as there are too many zombies. The housemates decide to stay in the house as long as possible. When Patrick insists on going forward, they tie him up. Patrick manages to turn Joplin against the others, reminiscent of the style used to change alliances between housemates in a non-zombie season of Big Brother. Joplin unties him and carries the bowl of bait while Patrick takes Kelly hostage, heading outside. Everyone follows him but in the struggle the bait is dropped and Patrick kills Riq. Pippa runs back to the studio's offices and Space follows. Joplin panics and opens the gates. He is attacked by the zombies as they flood inside the compound.

Kelly, Marky, Veronica and Patrick run for the house, but the zombies rip Patrick apart. Space makes it to the control room and communicates using the PA system. Zombies quickly fill the camera runs and Kelly realizes they will easily make it through the two-way glass and fire doors. She urges Space to open the diary room and he is bitten by the zombie of previous housemate Aisleyne. He manages to get into the innermost control booth and sees on the monitors that the zombies have forced their way into the house. Only Kelly makes it into the diary room, leaving Marky and Veronica to be eaten. Kelly congratulates Space on winning this series of Big Brother, and tells him to open the outside door so she can fight her way to the van. He refuses until he sees that Pippa is one of the zombies trying to get into the booth, alongside her undead mother. As soon as the diary room door is opened, Kelly screams and the camera cuts to black.

Next morning and Joplin, Marky, Space, Pippa and Veronica are seen as zombies; Joplin roams outside the studio gates; Marky and Veronica feast on the remains of Grayson; Space stares blankly around the control room. Finally, in the closing seconds, zombie Kelly stares into a camera in the Big Brother house, before the scene switches to a zombie in front of a television in a shopping centre somewhere in the United Kingdom - a rapt "viewer" of housemate Kelly and the Big Brother live feed on E4.