Barbie knows that even the smallest person can make a difference in the world, so when she leads a group of young children on a tree planting expedition in a nature preserve, she makes sure that each child knows that his or her action is important and meaningful. To illustrate her point, Barbie tells the kids the story of a young Twillerbee named Thumbelina who vowed to save her people and their world from destruction in spite of enormous odds. When humans Evan and Vanessa decide to raze an extensive flower field to build a new factory, their spoiled daughter Makena demands a patch of the flowers be brought home in hopes of impressing her equally spoiled friend Violet.