On Christmas Eve, Santa is accidentally knocked off his sleigh and arrives unexpectedly in Tom's fireplace. Dizzy and confused, Santa is unable to deliver any presents, so Tom and his monster pals step in to help.
In this latest adventure, Tom sneaks his monster pals in his suitcase and takes them on the family holiday. Meanwhile Moggie McNab, whose partner in crime is the infamous Count, steals "The Moping Marjory", a famous painting from the local art gallery. Can Tom and the monsters solve the crime and return the paintings to their rightful owner?
