Egon, Ray, and Peter Venkman are fired from their university positions due to their unconventional research and alleged misuse of grant funds. This leads them to found Ghostbusters, a paranormal investigation and elimination service, operating out of an old firehouse.

The Ghostbusters face their first major paranormal threat: Gozer the Gozerian. Egon plays a crucial role in understanding Gozer's dimensional portal and developing a plan to cross the streams of their proton packs to seal it, saving New York City. His quick thinking and scientific knowledge prove vital.

The Ghostbusters experience a period of high demand and success. They become local heroes, battling various ghosts and paranormal entities. Egon continues to refine their equipment and develop new ghostbusting technologies. He also begins to experience more social interaction, although he often struggles with social cues.

The Ghostbusters confront Vigo the Carpathian, a powerful 16th-century tyrant attempting to return to life through a painting at the Manhattan Museum of Art. Egon contributes significantly to the scientific understanding of Vigo's power source (mood slime) and develops methods to counter it. This event further solidifies his reputation as a brilliant scientist.

With a decrease in paranormal activity and increased legal challenges, the Ghostbusters face financial difficulties. The team begins to drift apart, although they maintain contact. Egon continues to pursue scientific research, focusing on alternative energy sources and theoretical physics.