Santa Claus is suffering from a mysterious disease. He lies in bed and only repeats one word: Lebanna. The elves are desperate and don't know what to do anymore. Christmas seems lost when Santa's assistant Annabel uses magic and summons the greatest detective on earth to the castle. The man who appears in front of her doesn't seem very smart but she claims to be the great-great grandson of the great Sherlock Holmes. Annabel entrusts him with the case and an assistant to her, her son Sam. Will the two be able to solve the Lebanna mystery despite Sherlock being allergic to Christmas? Maybe the solution lies in some Arctic Friends cartoons that Santa watched as a child?