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.

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.