Goya is a little mouse who wanders the streets of Paris in search for food. A cloud of exhaust fumes forces her to take refuge in a cellar. In this cellar, a luminous point calls to her, Goya approaches and is suddenly sucked in. It is a time portal taking her to a future where humans have disappeared because of ecological disasters. This world is run by those who have survived: small, lilliputian animals who have managed to hide from bigger catastrophes, in the same way they did when the dinosaurs disappeared. In this world, everything has to be done again, but better this time. Nature offers a second chance.
The next day, Goya meets Chloro, the spirit of the forest, who guides him into the world of Harmonia. Goya meets these inhabitants: Byzance, Gaudi, Argos, Demet, Abry, Chanelle, and Gretto.
Everything seems to be idyllic, but the Harmonians are unusually discreet about Rusk, the squirrel that occupied Goya's house. Who really was Rusk? Where did he go, where and why?