Reed summons one of his deep space probes back to the Baxter Building for repairs, only to find that someone has hitched a ride on it back to Earth: the Impossible Man! The small, impish alien seems harmless enough, but the Fantastic Four soon realize that this creature, who can turn into anything, has turned into a big problem for them! Now they have to figure out how to get the Impossible Man off the planet before he goes from 'annoying' to 'dangerous!'