Marc Winters' sister Issy died 8 years ago, during the catastrophic end of the cult she belonged to. They believed that they could hold back the increasing impact of climate change by dreaming a new world into existence, fuelled by psychotropic mushrooms. But the dream ended in disaster. Winters has kept his head down since then. He had his own connection to the cult, and was viewed with suspicion by his friends, family and the authorities. Now he lives a quiet, anonymous life as the wildlife ranger looking after a small island in the Blackwater Estuary in Essex, attempting to revive the biodiversity of his small patch of ground. Too many species have gone extinct, or are on the brink of disappearing, but he and his colleagues are doing what they can, while they can. But then an unexpected visitor to the island needs to be rescued from drowning, Winters' narrowboat is burgled and graffitied, and the police come calling again. Something unexpected is happening, and perhaps the dreamers' cult is not as finished as everyone thought. Across the familiar but impossibly changed landscapes of England after decades of climate catastrophe, Winters must investigate these strange events, and discover the true fate of his beloved sister.