The day before Christmas, Billy, Mandy and Grim go to the shopping mall, where Mandy complains that Santa Claus is just an invention from corporations. However, Grim assures Mandy that Santa is real, and they even went to college together. Then, they decide to travel to the North Pole and meet Santa, but when they arrive Mrs. Claus (Carol Kane) tells them that Santa Claus (Gilbert Gottfried) has been transformed into a vicious vampire. Then, to save Christmas, Mandy and Grim go to stake the Head Vampire, Baron Von Ghoulish (Malcolm McDowell), while Billy remains with Mrs. Claus to look after her. However, it turns out that the cleaning-obsessed Von Ghoulish is not the vampire they are looking for, so they set out to find the Head Head Vampire. Then, Mandy, Grim and Von Ghoulish go back to Santa's workshop where it is revealed that Mrs. Claus is in fact the Head Head Vampire, and it was she who transformed Santa, which she did so she could take a break from all her work. Then, Billy finds holographic instructions to bake cookies, which he gives to the vampire Santa Claus, restoring him to normal. Finally, Mrs. Claus and Mandy prepare for a final confrontation, but Santa arrives on time to reconcile with his wife. In the end, Santa acknowledges he married his wife even though she was a vampire long before they met, and that she has turned him into a vampire many times before, (six or seven times in fact), but he always manages to recover.