Cosmium is a gravity-repelling metal mined on Pluto and reduced to a substance called Gravitex. Nucleo, the Mad Martian, is suspected to be responsible of the theft of large amounts of the Gravitex. Pojo is a henchman of Nucleo, who helps Nucleo in the crime. Commodore Rex Clive and Stella Dawn assist the Space Rangers in capturing Nucleo and his henchman, Pojo.