This film explores the species-area relationship, a general ecological rule that describes how the number of species in a habitat changes with area, and shows how it has been applied to the conservation of protected areas.

Habitats are shrinking and becoming more fragmented due to human activities, leading to the loss of many species. One tool that scientists are using to conserve Earth's remaining biodiversity is the species-area relationship. The film begins with the story of ant biologist E. O. Wilson, who observed and tested the species-area relationship on islands. It then shows how Wilson's findings have been expanded and applied to "islands" on land, including habitat fragments in the Amazon rainforest and Rocky Mountains. These studies have revealed the importance of preserving and connecting protected areas for wildlife.