In the country nearby London, Don, his wife Alice and a few survivors live hidden in a farmhouse. When infected people break in the house, Don panics and does not help his wife to escape, running away and leaving Alice trapped inside the room. Twenty eight weeks after the outbreak that annihilated the population of Great Britain, London is considered safe and the British survivors return under the coordination of the American Army, that keeps the city under permanent surveillance. The teenager Tammy and her younger brother Andy travel back from Spain to live with their father Don in London. They miss their mother and decide to escape to their old house to retrieve pictures and some other personal belongings. However, they find Alice surprisingly alive and the Army brings her to the base. After some blood test, the biologist Scarlet discovers that Alice is a carrier of the lethal virus and somehow has immunity to it...