In Morriston Hospital in Swansea in 1994 a group of ordinary middle-aged Welsh men stepped into the unknown by taking part in the world's first medical trials for the drug that became Viagra.
As London is submerged below floodwaters, a woman gives birth to her first child. Days later, she and her baby are forced to leave their home in search of safety. They head north through a newly dangerous country seeking refuge from place to place.
In a ruined and toxic future, thousands live in a giant silo deep underground. After its sheriff breaks a cardinal rule and residents die mysteriously, engineer Juliette starts to uncover shocking secrets and the truth about the silo.