The aggressive actions of men on the environment have endangered the biodiversity of a world which seemed inexhaustible. Ecosystems are being lost, oceans overexploited, species exterminated... However, in the midst of so much discouraging news, there are also actions filled with hope being taken by people and institutions who are unwilling to resign themselves and who, day by day, achieve extraordinary success in caring for and preserving nature. Species which have been saved from extinction, forests which are sprouting again thanks to the education of and care taken by indigenous people, research and technology which manage to recover lost species ; large animals such as whales and rhinoceros and diminutive creatures such as krill and hummingbirds ; jungles and deserts, glaciers and prehistoric forests. Addressing problems ranging from the hole in the ozone layer to the biodiversity in a square metre of tropical rainforest, we will see fabulous animals, paradises threatened by man’s intrusion, remote regions and icy worlds where species proliferate far-removed from the threat of humans ; a world of dangers and direct actions which will bring hope to a world whose future depends to a large extent on the work of these pioneer keepers.