After an alien spaceship crashes in a secluded park, hungry mosquitoes swarm around the dying aliens. Megan (Rachel Loiselle), a rookie park ranger, and her boyfriend, Ray (Tim Lovelace), are camping in the same park when they make a terrifying discovery: the mosquitoes have undergone a genetic mutation and transformed into enormous, deadly creatures. Megan and Ray team up with a clumsy park ranger (Ron Asheton) and a mysterious survivalist (Gunnar Hansen) to defeat the insects.