A mysterious Front, originating in Scotland and slowly expanding outward, threatens humanity's existence. In defiance of the known laws of physics, it only kills humans and is otherwise undetectable. Panic-stricken nations struggle against both the advancing menace and a tide of civil unrest. Desperate individuals must find their own paths, and find them quickly. Although very slow, the Front can be deceptively difficult to escape. Mankind has only a few years to pool its rapidly dwindling resources and save itself from extinction. Amid growing chaos, the novel follows the choices made by a Glaswegian shopkeeper fleeing her rioting city, two National Guardsmen facing an impossible situation in the mountains of Colorado, a young girl whose family is disintegrating around her, and a desperate Chinese prisoner facing the unknown. A last ditch effort by a brilliant scientist and her inexperienced protege may represent humanity's only hope. Through the lens of these lives, and a variety of other stories, essays, and TV transcripts, we experience a world struggling to come to grips with its impending mortality. Prisoners are sacrificed, governments bomb their own people to halt the waves of refugees, suicidal sports form, and life becomes a race for survival against the slowest but surest of enemies.