From the burning deserts to the icy steppes of the poles, from the green meadows to the tropical forests, insects occupy every ecosystem on the planet. An astonishing, fascinating and yet long ignored world. Who are they? Where do they come from? When did they first appear? How and why have they diversified and multiplied so much? Today, new methods in paleo-entomology, in the exploration and analysis of fossils and living organisms reveal the extent to which insects have contributed to shaping our world. They have even participated in the evolution of humans. At a time when some of their species are in danger of extinction and their place in ecosystems is being questioned, this film tells the fascinating story of the mysterious insects and the secret of their origins.