惊变28周

The film opens with Don and his wife Alice in an English cottage sheltering from the Rage virus that has ravaged Great Britain. Together, with a variety of survivors as they sit down to a quiet meal, a young boy can be heard shouting and banging the door from the other side in desperation. Against everyone's wishes, Don opens the door and lets the frightened child in, who reveals how he managed to escape the Infected. But this peace is short lived when one of the survivors is attacked by the Infected, thus turning her and leading to an attempted attack on another survivor and Don kills her with a crowbar. Suddenly, the Infected barge in and the survivors flee the cottage. Everybody is presumed killed or infected except for Don, who flees and leaves his wife and the young boy to die in a moment of panic. Escaping from the infected, he hijacks a small boat and speeds away. Titles appear, outlining the timeline from the outbreak of infection through the quarantine of Britain, the last of the infected dying of starvation, the arrival of American-led NATO troops, the planning of repopulating and finally 28 weeks later...

Scarlett, a US Army Medical Officer, watches a single plane land in London. Among the people that have arrived are teenager Tammy and her younger brother Andy. Everyone undergoes several health inspections, and Scarlett notices that Andy has heterochromia, a trait he inherited from his mother. Americans Doyle and Flynn are introduced also: Doyle a wisecracking sniper and Flynn, a helicopter pilot and family man away from his family. Andy and Tammy are moved into District 1, a fully-functional section of London city, located in the Docklands area known as the Isle of Dogs. The children are reunited with their father, who turns out to be Don from the beginning of the film. He explains that their mother was killed and that he could do nothing about it. Later, the children decide to leave the safety area to return home to collect a picture of their mother. At the house, they discover that Alice is still alive and has been hiding in their attic in a traumatized state. Scarlett does a blood test on Alice, which reveals that she is infected but is somehow immune to the virus. It is suggested that her genes repel the Rage virus' symptoms; however, she is still technically a carrier.

Don finds out about his wife after seeing his children and visits the operating theatre where she is tied down unguarded. He begs for forgiveness and she accepts. While exchanging a kiss, Don becomes infected. He kills her in his rage and breaks out of the area and into District 1, quickly attacking soldiers within proximity. A code red is ordered when it becomes clear that the virus is active again. Scarlett rescues Tammy and Andy from containment and they flee together, though Andy becomes separated in the chaos. British civilians, including Andy, are moved underground but Don attacks them, causing mass panic and hundreds more are infected in the chaos. Doyle is given the order to take out as many of the infected as possible, but his orders are soon changed and he is told to kill anybody and everybody - including the uninfected, which shocks him.

Andy escapes the crowd into a safe area with others who have not been infected, where he is reunited with Tammy and Scarlett. It is revealed that Doyle has left his sniping post and is joining the group of survivors on the ground to help get Andy and Tammy to safety. He tells them he will lead them to safety. While attempting to escape, they find themselves being shot at by the American soldiers and fighting against the infected. Flynn contacts Doyle and tells him that in four minutes the district will be firebombed and that they need to escape. They do so, hiding in a tunnel, dodging the attack as a section of London is destroyed. Later, in an abandoned park, Scarlett informs Doyle that the key to curing infection is in the children and they agree that they must do what they can to deliver them safely. Flynn arrives to pick Doyle up and only wishes to take Doyle and no one else, refusing to negotiate. A large group of the infected who are docking on the horizon give chase. After slaughtering many of the infected with the helicopter blades, Flynn flies away, assigning Wembley Stadium as the new pick-up point and telling Doyle to meet him alone.

They climb into a car to escape the chemical gases being pumped into the streets and Doyle is killed in self-sacrifice when he attempts to save them by push starting the car. Scarlett drives the car away and the remaining trio enter the London Underground. Using the night vision scope on Doyle's assault rifle, Scarlett steers them all down into the underground tunnels but is attacked and beaten to death by an infected who is revealed to be Don, who continues to attack his own son and bites him. Tammy is forced to kill her infected father. Andy, though bitten, remains without symptoms like his mother. The two continue to escape and are picked up by Flynn at Wembley Stadium. Flynn flies them to safety as they pass the burning ruins of District 1 and eventually over the White Cliffs of Dover and into France.

28 days later, the remains of the helicopter are contrasted against images of Paris, France and someone calling out for help in French accented English. In the last scene, the infected rush through the Palais de Chaillot towards the Eiffel Tower.