The brilliant scientist and inventor Seth Brundle invites the journalist Veronica Quaife to her laboratory to demonstrate her scientific work. He suggests the girl to be a chronicler of all his experiments and record the most important interviews. Soon, a romance flares up between them. Once there is a fatal mistake - Seth decided to conduct an experiment on teleportation on himself. During the experiment, the computer produced the fusion of the common fly and Seth at the genetic-molecular level, after which the scientist began to mutate. Begin irreversible changes in his body - both internal and external. Veronica soon learns about what happened, but the situation is further aggravated by the fact that she is pregnant with Seth, who gradually turns into a monster.