Once upon a time, Thumbelina was born in a blossom. The little girl's adventure starts when a bumblebee opens the flower. Thumbelina has to hide in a nutshell from a toad who is eager to get married and she lands on a water-lily leaf. A fish cuts the stem of the lily and she has to swim in the creek. Thumbelina is saved by a maybug who asks her for a dance. But the dance does not work out and Thumbelina falls from the leaf into a spiderweb and into a dandelion. Holding onto a seed, she sails away and lands in her blossom.

When a fall storm breaks her flower, she finds shelter with a field mouse. Here she nurses an ill swallow. The field mouse keeps pushing Thumbelina into the marriage, saying the mole is a good match for her. At the last minute, Thumbelina escapes the situation by fleeing to the sunny south with the swallow.

This animated film is based on Hans Christian Andersen's fairy tale.