In the vastness of space, a spaceship shaped like a slice of cheese races between galaxies in search of new planets and strange aliens! It is the Top Galaxy, the spaceship of the Cosmo-Mice, the fearless space mice, who travel the universe with their unique captain, Geronimo Stiltonix!

The aliens of the planet Diaphanix buy new things every day and throw away whatever they purchased the previous day. Among the garbage, there are also many robots. But the discarded robots are rebelling… The Cosmo-Mice must restore peace to the planet!

The brave Cosmo-Mice traverse space in the Top Galaxy, a mouse-tastic spaceship shaped like a slice of cheese. Here, the crew has all the necessary comforts: ultra-luxurious cabins, restaurants, greenhouses for growing plants, libraries, theaters, amusement parks, gyms, sports fields, and even a biosphere that replicates various natural environments!