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.

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.

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.