 The first few books cover Rourke's attempts to find his family, on the way fighting invading Soviet troops as well as typical post-apocalyptic villains such as biker gangs, mutants and cannibals in extended scenes of graphic violence.Later books head more into science fiction with cryonics, doomsday weapons and underwater cities.Starting in 2007, audio versions started to be released by Graphic Audio covering the entire series of novels.