This documentary explores the relationship between life in caves and the forest above them. Narrated by the world's foremost biospeleologists, they program provides an intimate profile of the organisms that inhabit the spectacular caves of southern Indiana. Drawing on their individual areas of expertise, the scientists describe how cave conditions have shaped the animals over evolutionary time. From bats to bacteria, the connections between different groups of organisms are revealed. The program strives to produce a comprehensive picture of the cave ecosystem, emphasizing the role of the forest and weather on the cycle of life in a subterranean environment.