In a land where every holiday has its own isolated locale and citizenry, Jack Skellington (voice of CHRIS SARANDON, singing voice by DANNY ELFMAN) is the Pumpkin King of Halloweentown, a drab and dreary place of ghouls and goblins where everything revolves around the last day of October. The following day, the two-faced Mayor (voice of GLENN SHADIX) wants to discuss his plans for the following year, but Jack is nowhere to be found.
Looking for something more in his life than just scaring people, Jack has wandered off into a remote forest where he comes across the entrances to the many holidays and is swept into Christmastown. There, he's fascinated by the colorful sights and enraptured by the holiday spirit. Beaming with a new sense of purpose, Jack returns home to share the news of his discovery, including that of Santa Claus, whom Jack misinterprets as the malevolent and monstrous dictator, Sandy Claws.
Although most everyone is mesmerized by Jack's description of this place, Sally (voice of CATHERINE O'HARA) - a rag doll stitched together by her Dr. Frankenstein type creator, the Evil Scientist (voice of WILLIAM HICKEY) - isn't so sure if his plans on taking over Christmas are wise or sound. Nonetheless, Jack sends the town's trick-or-treaters, Lock (voice of PAUL REUBENS), Shock (voice of CATHERINE O'HARA) and Barrel (voice of DANNY ELFMAN) - who serve the malevolent underworld figure, Oogie Boogie (voice of KEN PAGE) - to kidnap the real Santa.
With Saint Nick out of the way, Jack decides he'll play Santa and deliver Halloweentown's version of macabre presents to the boys and girls of Christmastown. When that goes disastrously wrong, Jack must figure what to do, as well as save Santa and Sally from the clutches of Oogie Boogie.