On Christmas Eve, Jack and Annie’s tree house transports them to King Arthur’s castle in
Camelot. They arrive to find that all is not well in Camelot, Merlin has been banned, and all
magic use is forbidden. Many of the bravest knights have been lost on a mysterious quest to
the Otherworld. The Christmas feast is interrupted by a knight, who sets a challenge to find
the knights and break the curse. He demands to know “Who will go?” Annie, naturally,
accepts. She and Jack set out on a quest to the Otherworld, to bring back magic and joy to
Camelot.
— based on fandom.com