When an alien unicorn descends to Earth, its mission morphs from embedded surveillance of an Earth family to just plain fun. Bubble07's log entries, addressed "Dear Fearless Leader," comprise the narration. "You were right. We look exactly like the toy animals here." Should the unicorn army invade Earth? To find out, Bubble07 wriggles into an arcade's glass box full of plushy prizes and gets hooked by a dad for his daughter. (Dad and daughter present Black; mom, seen later, is a woman of color.) About Earthling Daughter, Bubble07 reports: "She loves her toys. She loves them to pieces! Some are missing their eyeballs. Is this going to happen to me?" Biedrzycki's expert illustrations form a hilarious counterpoint to the alien's clueless reportage. They begin in grayscale, accented by Bubble07's otherworldly streams of neon-hued sparkles, as the spy experiences family camping and "show and share" at school. The jealous family sheepdog tries to bury Bubble07 in the backyard, but revenge is sweet: At night, discovering "amazing" peanut butter cookies, the spy leaves the empty bag next to the sleeping dog. "Fearless Leader…I must get this cookie recipe for our planet." By Day 50, a snow day, full-color spreads depict the unicorn integrating into family life, experiencing Earthling Daughter's birthday, cuddly bedtime stories, and a sick day as stand-in comfort animal. On the home planet, Bubble07's final report recommends: "forget the invasion and send more of us to Earth for… / …a Unicorn Vacation!" Simply delightful (with a wry final twist). (Picture book. 4-8) Copyright (c) Kirkus Reviews, used with permission.