The world is losing more than animal and plant species. We are also losing the vast human legacy of languages, and with it ways of living, seeing and knowing. Terry Glavin sets off in pursuit of endangered species, and finds hope in the most unlikely places: a macaw roost in Costa Rica; a relic community of Norse whalers; a vault beneath the Royal Botanical Garden at Kew. As he explores the history of extinctions, Glavin uncovers the hidden story of a long human struggle to conserve the living things of the world.