In this all-new very special mini-series, the Aldens have been recruited by a secret society to return lost artifacts and treasures to their rightful locations—all around the world! After finding a painted turtle figurine, the Aldens are introduced to the Silverton family and Reddimus Society, a secret guild whose mission is to return lost artifacts and treasures to the sites they were taken from. The Aldens board a private train to New Mexico to return the turtle to its original home, and they encounter enemies of Reddimus along the way! The trip is a success... but instead of returning home, there's a last-minute change in plans. The Boxcar Children must continue the mission for the society and deliver more things, all around the globe!