When a seemingly uneventful visit to your brother turns into a hotbed of conflict between humans and Clouders it will be up to you — Mary Gilbert — famous botanist and guardian of Fern Flower — to once more enter the magical world of eastern European deities, ancient beliefs and mythical lands.

Accompanied by Aitvar, a house spirit, set off to the other end of the rainbow, where a flying city floats among the clouds and where your brother is being held captive by an evil sorcerer. Save him and together renew the ancient covenant between humans and Clouders. Will cleverness and resourcefulness be enough to overcome sinister Zmeys on the sorcerer's service and prove your worth to Perun, the god of thunder? Will you be able to save the earth before it gets flooded by the ocean?