Three intrepid middle schoolers and a hamster who, unfortunately, talks set out on a last, desperate mission to save humanity.It seems that the seven civilizations, including ours, have been suddenly emptied of their sentient races by the ruthless Elvidian dictator dubbed the Minister, and only Public School Spaceship 118, piloted by hotshot 13-year-olds Ari, Becka, and Jack, has a chance of eluding the teeming Elvidian war fleets to secretly plant in each system the high-tech devices that can restore the missing populations. Luckily (as it turns out), the trio gets some unexpected help after Doctor Shrew, Ari's beloved hamster, passes through a mysterious beam and emerges able to make outrageous-but who (or, more properly, Who) knows, maybe justified-demands to be recognized as a "Scion of the Old Ones" and an "immortal time-traveling hamster god." Levy artfully folds serious personal and parental issues into his less-than-serious round of chases, narrow squeaks, team building, and (poorly choreographed, but aren't they all?) space battles on the way to a happy resolution and a delayed but properly heartwarming eighth grade graduation ceremony. Along with a temperamental, pun-loving AI, the cast includes a nonbinary student and other cues of diversity; dark-skinned Ari has two dads and is Jewish.Typical middle-school-in-space experiences with a bit of worlds-saving and maybe the odd Time Lord thrown in. (Science fiction. 9-13)