She is the best-kept Christmas secret of all,’ whispered Santa Claus. ‘Which is surprising, because Christmas itself would not exist without her. She is older than time itself, yet still as young as tomorrow. She is known only as the Winter Witch.’

One year has passed since William Trundle’s incredible adventure with the most extraordinary dinosaur: the Christmasaurus. Now, William is swept back to the magical North Pole, where he meets the mysterious, icy Winter Witch – whose power to control time allows Santa Claus to make the long journey all around the world every Christmas Eve.

And when they learn that the fate of Christmas itself hangs in the balance, William and the Christmasaurus must work with the Winter Witch to protect it…