From Dav Pilkey, the worldwide bestselling author-illustrator of Dog Man, and award-winning illustrator Dan Santat comes an out-of-this-world friendship adventure in full color!Having a big best friend isn't always big fun...Ricky Ricotta loves his Mighty Robot. They do everything together, but it's sometimes hard for a small mouse to have such a big buddy! If only the Mighty Robot could find someone his own size to play with, Ricky might finally have some fun by himself.Little does Ricky know, his wish is about to come true. Evil Uncle Unicorn has a top-secret plan to trap the Mighty Robot so that he can take over Earth, and he's got a giant surprise in store. Once again, it's up to Ricky to save the planet -- and his best friend!