After the mice defeat the wicked aliens and their super-ultra evil leader named Kim Crupply in the original Space Mice book, they are greeted by yet another adventure to save Earth.

On Neptune, devious robots are forming a diabolical plan. The mice are in for a huge adventure involving: lasers, spaceships, and any other evil things. They will have to navigate through the most high-tech mechanisms and many deadly traps, weapons, and monsters.

Once again, the fate of the world rests in their tiny little hands. But will the mice make it in time? Will they even live to try? Find out in Space Mice 2 Neptunes Army.