After breaking into a primate research facility, a group of animal rights activists discover caged chimps chained up before banks of video screens displaying horrifically violent images. Ignoring the warnings of the terrified researcher who maintains the chimps are 'infected', they begin to free the animals and are immediately subjected to a bloody attack from the enraged creatures.

28 days later, cycle courier Jim (Cillian Murphy) awakes from a coma in the deserted intensive care unit of a London hospital. Mystified, he wanders the wards and corridors in search of others and eventually heads into the city streets, in search of help. As the shadows lengthen, Jim seeks shelter in a church only to find dead bodies piled in heaps on the chapel floor. A sudden noise alerts him to the presence of a priest but his lightning speed, bloodstained eyes and murderous screams send Jim reeling back out into the street. More "infected" people are attracted by the noise and Jim runs in panic and confusion as a growing flock sprint after him through the dark streets.

A sudden explosion from a makeshift bomb heralds the arrival of fellow "survivors" Selena (Naomie Harris) and Mark (Noah Huntley). After a daring rescue, they take Jim to safety and explain to him the nature of the infection, that it is transmitted in the blood and overwhelming within seconds, and that Britain has been overrun and that they have no way of knowing if it has spread worldwide. - www.28dayslater.com