Theodore, Dorothy, Jonas, Ursula, and Hugh have lived inside a cage their whole lives, cared for by a team of scientists who provided everything they could ever need. But their lives change overnight when the scientists perform an experiment to transform these five average lab mice into GEMs: genetically engineered mice. When they’re launched into orbit, the mice learn that the astronauts plan to leave them on the International Space Station—forever. The G.E.M.S. must band together and use their unique mutations to survive in outer space and change their destiny.