Glasgow, 2001. Along with a number of major cities in the UK, Glasgow is in the grip of a series of race riots, inflamed in particular by a recent influx of asylum seekers. Many of them are housed in a high-rise estate in one part of the city. A Kurdish refugee, Sherko, who has escaped from Iraqi persecution and who now lives with his daughter, Resa, in a flat on the estate, is worried by his daughter's persistent cough. During a visit by Robina, an employee of the Asylum Support Unit, he has to hurry away to find some menial work. Left to look after Resa, Robina also becomes worried by her health, and when Sherko returns, they take her to hospital, where she is diagnosed as having a bad dose of flu. However, another refugee from the estate has also been admitted with similar symptoms and later dies. A public meeting is held in the infirmary, where health officials attempt to reassure the immigrant community that there is no cause for alarm. Robina is unconvinced and offers to lend Sherko her video camera so he can monitor his daughter's progress. He refuses, not wanting to complain for fear of being deported.

When driving to see Sherko at his flat, Robina notices the amount of ashes in the atmosphere that are blowing into her car. After expressing her worries to the Environmental Health Officer and enquiring about possible causes, she visits a local incinerator and attempts to get inside the premises, an action which brings her to the attention of the police. Her boss, Billy, the Asylum Support Co-ordinator, is outraged by her action and accuses her of irresponsibly trying to stir up trouble in an already tense situation.

As the street riots intensify to levels not seen since the 1980s, the outbreak of illness among the immigrant community on the Glasgow estate reaches epidemic proportions.Resa is befriended by a nurse, Annie, in the hospital and tells her of her memories of the frightening journey from her homeland to Scotland: her dream destination is Hawaii. While trying to keep the hospital operable and also contain the panic, officials are informed that tests have confirmed their worst suspicions: the patient was killed by the deadly germ anthrax. Unprecedented emergency measures are put in place, but officials are still uncertain how the germ got into the atmosphere and why only this section of the community is being affected.

Having believed that an environmental health hazard had occurred, Robina now suspects that some form of biological terrorism is taking place, and that the authorities are trying to cover up the extent of the danger. Her forthright opinions bring her into open conflict with her boss, who accuses her of self-righteousness and hypocrisy, and she leaves her job in a rage. Meanwhile, the team investigating the epidemic has been joined by a Senior Officer from the Anti-Terrorist squad. A neo-Nazi group called White Power has claimed responsibility, releasing e-mails featuring images of livestock which had died from anthrax and threatening further biological strikes if their demand for the expulsion of immigrants within an agreed deadline is not met. However, when other right-wing groups also claim responsibility, attention shifts to the possibility that a sole individual might be responsible. The health of people in the hospital, both patients and staff, continues to deteriorate.

As the crisis on the street deepens and curfews are imposed, Sherko removes his seriously ill daughter from the hospital; she collapses in the street. With his own apartment now trashed and the estate cordoned off, he carries his daughter to Robina's home, where she is following broadcast instructions to seal all doors and windows with masking tape as protection against the deadly germ. Together they make a drink of hot chocolate for Resa, laced with morphine tablets given to him by Annie to ease the pain in the last stages of her illness. A news report states that the police have raided the home of an engineer and seized a number of tapes. The man himself has escaped and the public is warned not to approach him as he is extremely dangerous.