Hermie Wormsworth must leave the Wallaceburg Library and hitch a ride to Miss Charlotte's to be at her house for Christmas Eve to meet Santa Claus. Hermie stows away on Santa's sleigh riding in Santa's pocket. He rides all night with Santa and arrives at the North Pole on Christmas morning. He meets Santa and Mrs. Claus and they discover that, The Christmas Book is missing. Santa is in a panic. Hermie decides to help Santa find the book. They begin with Henry the librarian and have many surprises along the way. Who is the thief and why was the book taken? The mystery deepens as the day begins to end. They must find the book before nightfall or Santa's dinner party will be ruined.