The Fly - By - Nights

150 years ago the world ended. Bombs fell, winter came, and the survivors fled underground in search of safety. Now they struggle to preserve what's left - sleeping by day, and battling fearsome vampiric fly-by-nights after sunset. Resources are scarce and security is scarcer in this fallout-poisoned world, but one subterranean clan of hardy souls clings to life, scavenging and scraping by until their water supply goes catastrophically bad.
Forced to seek a new life above, they leave their long-time home to caravan across the stricken planet's surface, where the light is toxic and the night hides unspeakable monsters. It is a difficult existence without promise or direction, until word from a band of fellow refugees fizzes through the choppy radio static. The Kindred promise help, companionship, and a new settlement in a distant valley .
if only the clan can reach them. For between the Kindred and the Clan stand a hundred miles of impossible terrain and countless fly-by-nights, and within the Clan itself trouble brews when two very different men fight for the love of one woman who has already made her choice. It's the oldest story ever told, but this time it could mean the end of humanity.