This the third movie in the series 28 days, 28 days later, and now 28 weeks later. All of these movies deal with a period of time after an outbreak in London and the surrounding areas. From what I can remember of the first two movies, there might have been one or two deranged people, but for the most part, the main characters had some common sense.
As this movie opens, there is a farm house in the country and the occupants are getting cabin fever after being confined there for a number of weeks. I should have taken a clue from the dumb girl in the beginning, pining for lost boyfriend, who gave away their location to the rage infected zombies. For the rest of the movie, I was annoyed by the two children who consistently acted in a way to endanger their lives and the lives of the adults trying to keep them safe. The 28 weeks later outbreak was pretty much the fault of the two disobedient, hard-headed kids. By the end of the movie, I was wishing that something would happen to them. That is how exasperated I was with their behavior.
Maybe I am too hard hearted or too much of a realist, but if a zombie apocalypse happens, there is no time to hesitate and try to save everybody. In a stress filled situation, not staying with the group will increase your chances of getting killed. If you do not listen when instructed to stay with the group, you get left behind. PERIOD. None of this “they are only children” nonsense. If they are tweens and teenagers like the kids in this movie, then they are old enough to understand what they are being told to do.