Mark O’Connell, whose book To Be a Machine won the Wellcome Book Prize, describes his new project as ‘a personal journey to the end of the world and back’ – in which his own worries about looming devastation feed into his travels among those who are determinedly preparing to face the apocalypse. Ranging from mountains in Scotland and bunkers in South Dakota to the lush valleys of New Zealand, O’Connell’s  encounters with environmentalists, survivalists, entrepreneurs and conspiracists is essential reading for the end of days.