In Brazil, in Africa, in Southeast Asia, and in the south of Europe, this film will follow the path of four mosquitoes, each of which is capable of transmitting viruses and dangerous parasites to humans. These mosquitoes are the carriers of dengue fever, malaria, Zika, and other infectious diseases. They take advantage of environmental changes, often caused by human activity, as well as a multitude of means of transportation, which help them to spread to new territories and threaten newfound populations. In the past, countries such as Japan and France, with their temperate climates were relatively free of danger, but now the first cases of autochthonous infections have brutally sprung up. These mosquitos are highly resistant to the protection strategies continually being developed by researchers. But scientists continue their field research, inventing new arms in the battle, each more surprising than the next. Facing the serious health risks they present us, humans have engaged in a fierce battle against the mosquitoes on the rise.