Did you know that there are Aliens living among us? You might have seen them around - they've got fur, whiskers, and a fondess for mice ...That's right, cats: a whole army of mean old moggies hell-bent on world domination. But don't worry, Earth's not going to give up without a fight. This little blue planet happens to have the best interplanetary canine defense force in the universe! The Spacemutts have a reluctant new recruit - Duke, a shy Great Dane. Eager to overpower the evil Lady Fluffkins, the gang fall into a trap, crash-landing right in the path of her equally evil sister. With their spaceship taken over by an army of ninja kittens, only a dog as huge as Duke can save the day!