The Thing in Mrs. Faversham's Attic

For seventy years, ghostly noises have emanated from the attic of a woman named Mrs. Agatha Faversham. She eventually hires the Ghostbusters to end this threat. Peter takes the case, for free, because Mrs. Faversham reminds him of his mother. However, what they find is a demonic spirit that was summoned up by Agatha's father, Charles, in order to try and give his young daughter a better life. However, unable to control the spirit, her father locked the creature in the attic and forbade his daughter from ever going up there. The Ghostbusters trick the spirit into revealing its true form and lure it into a ghost trap, with Slimer as bait.