The yeerks, a species of parasitic mind-controlling aliens have begun to invade Earth in secret. The andalites, a species of blue-furred centaurs, are trying to fend off the yeerks throughout several galaxies. They do so using the morphing power, which allows them to turn into animals- with certain limitations. A dying andalite shares this power with some human teenagers. PLOT HAPPENS.
A group of androids secretly live on Earth and have the ability to store Yeerks in their heads.