Dad often finds himself jumping up in frustration because of Lily. That's because she carries around the word "Why?" all day long. Dad dutifully answers Lily's endless "Why?" questions, but every now and then he gets a little annoyed and simply says, "That's just the way it is." Then one Friday, something truly strange happens. While playing in the sandbox at the park (still responding to everything with "Why?"), Lily and her dad spot an enormous spaceship descending from the sky. Aliens step out and announce to the people of Earth, "We have come to destroy your planet." As everyone trembles in fear, Lily simply asks, "Why?" The aliens are completely thrown off by her question. Arguing among themselves — "Why do we have to invade Earth, anyway?" — the aliens decide to return to their home planet to figure out the answer. Told through fun, comic-style illustrations, this book playfully captures how one clever little girl's simple question saves the world from alien invaders.