Buster is convinced that he's seen real UFO's, and he uses Muffy's fancy new telescope to get the proof. What he discovers is much more terrifying-a comet hurtling directly toward earth! Can Buster convince his friends that this sighting is real in time for them to save the planet? Mr. Sipple from next door is moving away and Arthur wonders-who will be the new neighbors? When Alberto Molina and his family settle in, Arthur makes a new friend and learns about a different culture...and about a comic book character named Conejitos Mechanicos! (That's Spanish for Bionic Bunny)