This mainstream documentary propels the viewer into the strange world of jellyfish. Animal that everyone knows for the threat it represents every summer on the beaches. But behind this seemingly simple problem, in reality much more complex mechanisms are hidden, and major ecological and economic issues as well ! What are these issues, what is happening in the oceans, what is the “jellyfish threat”? So many questions that this documentary will try to answer by giving the floor to various specialists, but also by inviting the viewer to dive under the surface of the Mediterranean and other seas, in order to discover the astonishing capacities of jellyfish. Because far from being passive and weak creatures, jellyfish are formidable predators capable of crossing oceans! Alternating underwater sequences and interviews with specialists, this film will be dynamic and entertaining. Rhythmic, educational without being boring, the film will gradually distill a great deal of information on the global mechanisms which led and which still lead to the explosive development of jellyfish.