Publisher Atari is referring to the new video game as "Ghostbusters III", continuing the action adventures of the paranormal investigative team.
The Mayor of New York has taken exception to the property damage that the team has caused and announces that money will be subtracted from the Ghostbusters' standard rate of $10,000 per assignment. At the end of each level, damages are deducted from your pay, with the less money earned, the less is available to buy new weapons and upgrades for the existing arsenal.
The first assignment is to investigate a disturbance at the New York Public Library, caused by the 'Gray Lady', alongside team members 'Ray', 'Peter' and 'Egon'.
After defeating the creature, the team finds a hidden stairwell, leading to caverns beneath the library, where various ghosts are pulled into a 'trap'.