Publisher's Synopsis
Five years after saving New York City from destruction by the demigod Gozer, the Ghostbusters have been sued for the property damage incurred and barred from investigating the supernatural, forcing them out of business. Raymond Stantz owns an occult bookstore and works a side job alongside Winston Zeddemore as unpopular children's entertainers. Egon Spengler works in a laboratory experimenting with human emotions, and Peter Venkman hosts a television show about psychics.
Dana Barrett, Peter's ex-girlfriend, has an infant son named Oscar with her ex-husband and works at an art museum cleaning paintings. She turns to the Ghostbusters for help after Oscar's baby stroller rolls, seemingly by itself, into a busy road intersection. At the museum, a portrait of Vigo the Carpathian, a brutal, sixteenth-century tyrant and powerful magician, comes to life and enslaves Dana's boss Janosz Poha. Vigo orders Janosz to bring him a child to possess, allowing him to escape the confines of his painting and live again to conquer the world. Because of his infatuation with Dana, Janosz chooses Oscar.
Meanwhile, the Ghostbusters excavate the intersection where Oscar's stroller stopped and discover a river of slime running through the abandoned Beach Pneumatic Transit system. Raymond obtains a sample but is attacked by the slime and accidentally kicks a power line, causing a citywide blackout. The Ghostbusters are arrested and taken to court for the damage and for investigating the supernatural. In the courtroom, the slime sample reacts to the judge's angry outburst, releasing the ghosts of two brothers he sentenced to death. The Ghostbusters capture the ghosts in exchange for a dismissal of the charges and the revocation of the order banning them from operating.
One night, the slime invades Dana's apartment, attacking her and Oscar. She seeks refuge with Peter and they rekindle their relationship. The Ghostbusters discover the slime reacts to emotions and suspect it has amassed from the negative attitudes of New Yorkers. While Peter and Dana have dinner, Egon, Raymond, and Winston explore the underground river of slime and are pulled in. They begin fighting until Egon realizes they are being influenced by the slime. They determine that the river of slime flows to the museum.