The Rubblebums are a vicious alien race, who have for centuries been prevented from invading earth by the protection of the Blue Galactic Stars. These stars contain a special stardust that is lethal to the Rubblebums. Finally, the Rubblebums have discovered a way to invade earth - destroy the stars. Using their Super Rubblebum Bubblegum gun, they have started to shoot down these stars which are falling to earth. Dr Goo has been asked to collect the fallen stars and put them back in their place, thus preventing a full-scale invasion of earth.