The series is set in a near future (roughly several decades into the 21st century) where ozone layer damage has forced all air travel to be abandoned (except for some airships), while the world is now spanned by an interconnected mega-motorway system called C3C. At the same time, global cooling has intensified, and large areas of the globe are covered in snow, inhospitable and difficult to cross, but also allowing land connections via the northern arctic.