Big Evil returns to Hauntquarters and curses Prime Evil with the Arcane Curse, a spell that can only be broken by performing a geniune heartfelt good deed. A battle between Prime Evil and Big Evil takes place at Ghost Command with no winner in sight for the Ghostbusters.

In the future the evil cyborg Cyman sends a ghostly being into the master computer of the Star Base Crusader in attempt to get revenge on Futura. The Ghostbusters travel to the future, shrink themselves down and enter the master computer, not knowing what lies ahead of them.

When Prime Evil sends Fangster to retrieve the Aztec Medallion, the Headless Horseman of Sleepy Hollow, a former hench-ghost of Prime Evil arrives at the Ghostbusters Ghost Command warning them of the danger. But can they trust him?

Prime Evil's latest plan to defeat the Ghostbusters has his ghosts travel to the future and reprogram Morrow's robot Roballos for evil. Back in the past, the Ghostbusters are surprised to find themselves attacked by robots they believed to be good.

When Prime Evil learns that Belfry wants to be bigger he disguises himself as the magician Monroe and hands him an amulet to help him. When Belfry shows the amulet to the Ghostbusters it shoots out a beam, shrinking them. Belfry must learn a valuable lesson as he helps Jessica and Futura save the Ghostbusters.

Eddie, wishing to be a great painter, asks Madame Why to conjure up some magic paints for him. When she refuses Prime Evil takes advantage of the situation and sends Eddie some magic paints. It is not long before Eddie has painted a masterpiece, a masterpiece that could lure the Ghostbusters to their doom.

Count Freeze arrives at Hauntquarters informing Prime Evil that he can defeat the Ghostbusters. Prime Evil agrees and it is not long before Jake and Tracy are frozen by the Count in Castle Blackstone. Unknown to the Wizard of Castle Blackstone, Prime Evil offers Eddie the chance to become a super hero.