Pollicina springs to life from a magic barleycorn planted by a childless woman, revealed fully formed within a sprouted flower. Her stature matches the length of a human thumb, and she resides in a walnut shell cradle lined with a rose petal blanket. Following her emergence, she enjoys peaceful days with her human mother until an elderly toad steals her away at night. The toad intends Pollicina as a bride for her son, imprisoning her on a lily pad in a pond. With aid from compassionate fish who chew through the lily pad's stem, she escapes, drifting away on the water.

Her journey continues when a beetle admires her beauty but later abandons her under pressure from fellow beetles. This rejection leaves Pollicina to survive alone in the wilderness through changing seasons. Facing near-starvation and cold in winter, she finds refuge with a field mouse. While living with the mouse, she encounters a neighboring mole whom the mouse pressures to marry Pollicina.

Within the mole's tunnel, Pollicina discovers an injured swallow. She secretly nurses the bird through the harsh winter, offering warmth and sustenance despite the field mouse's disapproval of birds. When the swallow recovers, it carries Pollicina from the impending marriage to a warmer land. There, she meets a flower-fairy prince of her own diminutive size. They marry, concluding her journey; the prince gifts her wings and the new name Maia.

Pollicina demonstrates compassion throughout, notably by aiding the swallow against the mouse's wishes. Her tale reaches a Danish writer via the swallow.