Bert, the cat Mellie adopted in series opener Rise of ZomBert (2020), may not be a zombie…but she's sure he's special. Former stray Bert has put on weight, and his fur's filled in in the month that fourth grader Mellie has been taking care of him. With him, she hopes to win the Best Pet Contest at the Lambert Harvest Festival (sponsored by omnipresent YummCo) so she can pay her parents back for Bert's vet bill. Her friend Danny's (kind of) helping with Bert's training while filming the rough-looking feline for a trilogy of ZomBert movies on social media. Bert has his own plan: to rescue all of his former test-subject companions from YummCo's labs. Meanwhile, the Big Boss and lab techs Kari and Greg scheme to get Bert (or Y-91, as they call him) back into the lab for more tests. Whose plans will succeed? Perspectives alternate chapter by chapter among Mellie (related in the first person) and Bert (in a third-person cat voice) and the Yumms (third-person bad guy), and the story moves at a nice clip. However, it's less spooky and mysterious than the first installment and has a truncated feel; it's definitely a middle chapter in a longer work, leaving little resolved. As seen in the illustrations, Mellie's family is interracial (she and her mom have brown skin and textured hair, and her dad and younger siblings present White); her friends are racially diverse. Entertaining enough, but young readers might want to wait until the final volume is out before picking up the first. As a stand-alone work, less than satisfying. (Science fiction. 6-10) Copyright (c) Kirkus Reviews, used with permission.