One afternoon, Micah comes home to find trouble taped to the refrigerator door. His parents claim it's a picture of his soon-to-be baby sister, but Micah is sure it's a Martian. When the baby arrives, his parents insist that she's perfectly precious - but Micah's no fool. He knows Martians do not come in peace. . . But in a laugh-out-loud Show and Share day at school, Micah learns how special a baby sister can really be.