Franklin's Aunt Lucy pays the family a surprise visit over the summer holidays. Aunt Lucy is an explorer whose speciality is finding archaeological treasures. Her visit prompts Franklin's Granny to recall burying a box filled with childhood mementos. When Granny suddenly falls ill, Aunt Lucy helps Franklin and his friends to find the box. The search for the box leads the friends through thrilling exploits in beautiful settings. Samantha, Aunt Lucy's goddaughter and a sassy young turtle, complicates things with her bossy behaviour. Franklin has to use all his diplomatic skills to keep things peaceful and focus on finding the box--and what is inside...