A king and queen, after some time, have a daughter. The king invites everyone to the christening, except his sister Princess Makemnoit, a spiteful and sour woman. She arrives without an invitation and curses the princess to have no gravity. Whenever the princess accidentally moves up in the air, she has to be brought down, and the wind is capable of carrying her off. As she grows, she never cries, and never can be brought to see the serious side of anything. The court philosophers, when consulted, are unable to propose any cure that the king and queen will suffer to be used.
She passionately loves swimming, and when she swims, she regains her gravity. This leads to the proposal that if she could be brought to cry, it might break the curse. But nothing can induce her to cry.
A prince from another country sets out to find a wife, but finds fault in every princess he finds. He had not intended to look at the light princess, but becoming lost in a forest, he finds the princess swimming. Thinking she is drowning, he "rescues" her, ending up with her in air, scolding him. He falls instantly in love and, at her demand, puts her back in the water, and goes swimming with her. Days pass, and the prince learns that her manner is changed between the water and the land, and he can not marry her as she is on land.
Princess Makemnoit, meanwhile, discovers that the princess loves the lake and sets out to dry it up. The water is drained from the lake, the springs are stopped up, and the rain ceases. Even babies no longer cry water.
As the lake dries up, they discover that the only way to stop it was to block up the hole the water is flowing from, and the only thing that will block it is a living man, who would die in the deed. The prince volunteers, on the condition that the princess keep him company while the lake fills.
The lake fills up. When the prince has almost drowned, the princess suddenly shrieks and frantically drags his body from the lake to take it to her old nurse, who is a wise woman. They tend him through the night, and he wakes at dawn. The princess falls to the floor and cries.
After the princess masters the art of walking, she marries the prince. Princess Makemnoit's house is undermined by the waters, and falls in, drowning her. The light princess and her prince have many children, none of whom ever lose their gravity.
Thumbs down to the movie version of this book. The combination of 1980's animation and real actors could be greatly improved with the latest technology. If you like fairy tales, this might be an interesting read.