Barney Thomson, awkward, diffident, Glasgow barber, lives a life of desperate mediocrity and his uninteresting life is about to go from 0 to 60 in five seconds, as he enters the grotesque and comically absurd world of the serial killer.

Life for former United Nations investigator Gerry Lane and his family seems content. Suddenly, the world is plagued by a mysterious infection turning whole human populations into rampaging mindless zombies. After barely escaping the chaos, Lane is persuaded to go on a mission to investigate this disease. What follows is a perilous trek around the world where Lane must brave horrific dangers and long odds to find answers before human civilization falls.