When Space mouse Geronimo Stiltonix helps an alien spacecraft get back to its home planet, their queen becomes enchanted by Geronimo, and tries to force him to marry her and stay on the planet Flurkon forever.

"The spacemice have received an invitation to participate in the intergalactic soccerix championship. It's a tournament for the most popular sport in space! But Geronimo doesn't even know how to play Soccerix, let alone lead a team to victory against aliens with bizarre skills (like flying)! Can the spacemice team prevail?"--Page 4 of cover.

While at the beach, Geronimo Stiltonix stumbles upon a mysterious treasure map. The spacemice follow it and end up on Aquarix, a planet that's entirely underwater. During their exploration, they face fur-eating seaweed, ferocious piranha aliens, and...pirate spacecats! Can the spacemice keep the spacecats from stealing the treasure?

Discovering that the gift-distributing Elfix aliens have disappeared as the Night of Dancing Stars approaches, Geronimo Stiltonix and his spacemice crewmates race to find the missing aliens before the celebration is ruined.

Geronimo Stiltonix takes MouseStar 1's broken computer to a distant planet to be repaired by a brilliant inventor, but pirate spacecats attack and steal the device, and the spacemice must retrieve it before the machine can be turned against them.

Geronimo discovers a planet on the radar that mysteriously appears and disappears. MouseStar 1 lands to investigate and they discover mysterious aliens who hide a secret!