Jim and Selena

Jim, completely shell-shocked, insists on trying to reach his parents’ house, despite Mark and Selena’s callous observations that his parents are most likely dead or Infected. Jim is adamant, however, and rather than let him go by himself (as he will almost certainly not return) the others reluctantly agree to accompany him. On arriving there, however, Jim finds that his parents have committed suicide together, believing that the world was over and that Jim would not wake up from his coma in the hospital. Shattered, Jim enjoys memories of living at home; but the candle he absent-mindedly lights attracts a couple of the Infected—two people, he is horrified to discover, who once were his next-door neighbours. Before the infected kill Jim, Mark and Selena arrived to kill the Infected, but Mark has been badly cut and blood from the attacker has mixed with his. Worried that he is infected, Selena instantly and ruthlessly hacks Mark to death with a machete, ignoring his pleads and screams. Jim is now almost as terrified of her, as Selena makes it clear that she will be more than willing to do the same for him "in a heartbeat" should he be infected. She informs him that once exposed to infected blood or saliva, a person has ten to twenty seconds before they become violent, thus enforcing Selena’s cold, hard-earned life philosophy—"staying alive’s as good as it gets."

Jim and Selena venture out once again, but are surprised to see a set of working Christmas lights in the window of a far-off tower block despite the fact that electric services have been discontinued for many weeks. They climb an improvised ladder fashioned from shopping trolleys that leads up to the main stairwell. The duo climbs the stairs, only to realize halfway up that Infected have followed them in. As Jim, who has fallen behind Selena, is about to be overtaken by the Infected, the two are rescued by an unknown man wearing police riot gear, who beats and kills the Infected on the staircase and ushers them into his flat. The man is Frank (Brendan Gleeson), a cabdriver, who introduces his teenage daughter, Hannah (Megan Burns). They have not seen anyone in weeks, and are only too happy to have Jim and Selena as company. A surreal and uncomfortable scene follows in which the group shares a bottle of Crème de Menthe, and Jim and Selena settle down in the flat for the night.

In the morning, Frank explains that they cannot survive in London, as they are running out of water—it has not rained in 10 days—and as Frank cannot leave Hannah alone in the building, they are thus surrounded by the Infected with dwindling food supplies. However, Frank has picked up a pre-recorded radio broadcast, running on a loop, made by a group of soldiers who have set up a fortified base at one of the army blockades built weeks before to protect Manchester. The message also claims the soldiers have "the answer to Infection." Deciding that Selena and Jim need Frank and Hannah as much as Frank and Hannah need them, the group eventually decides to leave London in Frank’s cab. The group go "shopping" at an abandoned supermarket for supplies and narrowly avoid the Infected on several occasions (including a tunnel under the Thames and a service station, where Jim is forced to kill a small boy who has been infected), and spend the night at the ruins of a castle. During their journey, the four bond as a slightly odd family, and it is clear that Selena, drawn into this family dynamic, is losing her pragmatic viewpoint on life.

While travelling along the motorway, they see that Manchester is engulfed by a massive firestorm, as there is no one left alive to fight the fires. They arrive at the blockade, only to find a deserted military camp strewn with dead soldiers and civilians; the blockade has been abandoned, which causes Frank to lose all hope. Storming away from the others, Frank is accidentally infected by a drop of tainted blood that lands in his eye. Realizing that he doesn’t have long to live, Frank tells Hannah that he loves her very much, and desperately pushes her away from him before he becomes an Infected. As the virus takes over him, he moves to attack them, but whilst Selena screams for the indecisive Jim to kill him while he has the chance, Frank is shot by several soldiers wearing NBC suits, who appear from nowhere.

The group of soldiers transport Jim, Selena, and Hannah to a nearby mansion fortified as a small military base. Their leader is the urbane Major Henry West (Christopher Eccleston), who explains that he and his seven soldiers are all that is left of the force which had been protecting Manchester, and that the fires in the city have driven hundreds of Infected into the nearby area, prompting his detachment to fortify the house. In an enclosed courtyard, Jim is shown Mailer, an infected soldier in chains, who is being kept by the major to determine how long it takes for the Infected to die from starvation.

Broken from the loss of Frank, Jim, Selena, and Hannah eat an uncomfortable meal with the soldiers, who - with the exception of the sergeant, Farrell, a solemn and conscientious man - are brash, crude and coarse. The soldiers are called from the meal to defend the house against a sudden attack by the Infected. After the attack (when a corporal, highly charged with adrenaline after the battle, attempts to force himself on Selena), Major West takes Jim aside, and explains that he cannot let the three of them leave; he has promised his lonely, suicidal and rebellious soldiers sexual access to women as a means of giving them hope, and of "rebuilding" the world. The "answer" to Infection involves waiting until the Infected have all starved to death, and in the mean time, luring whatever non-Infected they can to the base to acquire the women for little more than rape by the soldiers. Horrified, Jim tries to escape with his friends, but is knocked unconscious by one of the soldiers. When he wakes up, Major West offers one last chance to join them. When he refuses, he is thrown into the cellar with Sergeant Farrell, who has unsuccessfully tried to protect Jim and the women.

In the mansion’s bedrooms, Selena, having temporarily driven away the lust-fuelled soldiers, quickly convinces Hannah to take several pills of Valium so that she will not care about what will happen to her when sexually assaulted. However, the Corporal rushes back into the room and stops Selena from taking any pills herself and prepares to beat her as punishment. Before anything can happen, an air raid siren is heard coming from the blockade; Jim, outside the fences and thought dead by the soldiers, has managed to reach the blockade, and is waiting for them to come. West and another soldier make their way to the barricade and split up to look for Jim, while the rest wait back at the mansion with Selena and Hannah. As West and his comrade split up, Jim sabotages their jeep and kills the other soldier, stealing his rifle. As the Infected arrive, Jim heads back to the mansion in the jeep, leaving West to make his way back to the mansion on foot. Back at the mansion, Jim releases the infected Mailer by shooting his chains. Mailer escapes into the house and attacks his former comrades, infecting or killing the other soldiers present. Mailer attacks his first victim, vomiting blood on his face and causing him to be infected as well. Selena and Hannah then have their chance of escaping, but are caught, as they see Jones screaming and running, Mailer chasing him. A soldier is sent to kill Mailer, but the newly Infected pounces him and the two Infected attack the helpless soldier, breaking his neck. Jones, hiding in a cabinet, couldn't do anything but listen to the soldier's screaming. Hannah escapes from her captors and hides from the ensuing chaos.

Jones then comes out and sees the soldier's body and makes a run for it, but is stabbed by a bayonet from Jim. Jim then hears the Infected's screaming and runs to find Hannah and Selena. West returns and finds the stabbed soldier, after Jones has died, West wanted to take revenge for the deaths of his soldiers. Jim then finds a soldier hiding beside a bed. The Infected break into the room. Jim successfully escapes by the window, but leaves the soldier behind to be beaten to death by the infected. Selena, meanwhile, is still with the corporal, who is dragging her away; they are ambushed by Jim, who mercilessly takes revenge on the corporal by banging his head against the brick wall and then gouging his eyes out. Horrified, and believing Jim to be Infected, Selena tries to kill him; however, she has fallen in love with him and cannot bring herself to do it. Echoing her earlier words that her response was "longer than a heartbeat," she realizes that Jim is still himself, and they kiss passionately. Hannah, both drugged and also under the impression that Jim is infected, smashes a vase over his head. After clarifying the matter, the three run to the cab—only to be cornered by West who is waiting in the backseat. Blaming Jim for killing "his boys", he shoots him in the stomach. Hannah, at the wheel of the cab, steers him back into the house - where he is dragged, screaming, out of the back of the cab by Mailer and brutally beaten to death. Hannah and Selena rush Jim, who has been seriously injured, to a nearby hospital, but have a car accident before they reached the hospital.

The scene changes to the mountains of Cumbria, another twenty-eight days later. As predicted by West, the Infected are slowly dying from starvation. In the film’s coda (shot on 35mm film, unlike the rest of the film), Jim reawakens in a country cottage, to find Selena and Hannah, creating the word "hello" out of all the fabric they could find. They manage to attract the attention of a Finnish reconnaissance jet aircraft. As the pilot speaks to his superiors (requesting "Lähetätkö helikopterin?" or "Will you send a helicopter?"), Hannah and Selena begin to cheer and Jim slowly smiles. Although their fate, along with the fate of the rest of the country, is left open-ended, presumably parts of the world have escaped the infection.