A series of interlinked essays leads readers on a voyage that weaves through the themes of connection and estrangement between humans and nature. The journey shows how our modern lifestyles and economies would need six or eight Earths if the entire worlds population adopted our profligate ways. Pretty shows that we are rendering our own world inhospitable and so risk losing what it means to be human: unless we make substantial changes, Gaia threatens to become Grendel. Ultimately, however, the book offers glimpses of an optimistic future for humanity, in the very face of climate change and pending global environmental catastrophe.