When Seth Brundle makes a huge scientific and technological breakthrough in teleportation, he decides to test it on himself. Unbeknownst to him, a common housefly manages to get inside the device and the two become one.
Martin Brundle, born of the human/fly, is adopted by his father's place of employment (Bartok Inc.) while the employees simply wait for his mutant chromosomes to come out of their dormant state.
Industrialist François Delambre is called late at night by his sister-in-law, Helene Delambre, who tells him that she has just killed her husband, André. Reluctant at first, she eventually explains to the police that André invented a matter transportation apparatus and, while experimenting on himself, a fly entered the chamber during the matter transference.
Two dimwitted buddies hatch a money-making scheme after discovering an overgrown fly in the boot of a car.
Fifteen years after his father's experiments with matter transmission fail, Philippe Delambre and his uncle François attempt to create a matter transmission device on their own. However, their experiments have disastrous results, turning Philippe into a horrible half-man, half-fly creature.
While filming in Transylvania, a crew unearths celluloid images of a woman’s murder and unleashes the wrath of evil spirits.
The flower fairies help a little girl named Mary to thwart germs.