Twenty-eight days after a killer virus was accidentally unleashed from a British research facility, a small group of London survivors are caught in a desperate struggle to protect themselves from the infected. Carried by animals and humans, the virus turns those it infects into homicidal maniacs -- and it's absolutely impossible to contain.

DC Lenny Milton (Winstone) is not as ambitious as his best friend and popular boss DCI Michael Love (Dunbar), but the pair are drinking partners and their wives and children are close. However, this goes very wrong over the space of 7 days, when Milton is approached by the police complaints division asking him to go undercover and investigate allegations of corruption against his friend. Milton finds this difficult at first and tries to dismiss the evidence building up. But as his suspicions begin to take shape his position appears to be in danger.