Ten-year-old twins Matthew and Marissa are not thrilled about being pulled away from their friends to travel to New Mexico with their family. But when Matthew finds a curious old map under a cushion in their RV, everything changes. The mysterious parchment leads them through an amazing adventure, all of which takes place during the Albuquerque Balloon Fiesta. The twins face the challenges of solving clues to the map's puzzle, as well as overcoming distractions from their 4-year-old brother, David, who has autism. Marissa also reveals to us personal feelings and insight through her journal writings that are scattered throughout the book. Buckle up and enjoy the RV ride as you help Matthew and Marissa solve the puzzle in this Mysterious Journey!