When their newly developed disease, leopard spot fever, is perfected, it will wipe out the human race.

Thirteen year-old Crick and her best friend (a cockroach named Peri) embark on a desperate mission to stop them. Their mission takes them to tropical Panama, where the mosquito leader is marshalling her forces. But more than just mosquitoes await Crick and Peri, and soon they are running for their lives from the evil Dr. Dirk, in league with the mosquitoes. They must use all their wits and draw on a host of insect allies, but will it be enough to survive and stop the mosquitoes?