Kate might get to impress her scientist hero-if she can stop her saboteur.Fifth grader Kate, a White girl in a diverse school, loves chemistry. She loves science class, science projects, and watching her favorite pop scientist, Dr. Caroline, on YouTube. So she's overwhelmed when she learns that her school's received a grant to have a STEM night, and the judge they're flying in to evaluate the fifth grade science projects is Kate's beloved Dr. Caroline. Each of her friends knows immediately what science project they'll do. Elijah, a Black boy who loves drumming, explores sound quality. Birdie, a South Asian girl who loves art, experiments with ink chromatography. But Kate, who, in her own words, is "obsessed" with science, has no idea what to do. After a hubris-fueled false start, Kate gets a clever (and YouTube-ready) idea, but someone in the school is sabotaging her. Parts of her experiment keep being destroyed, and someone writes mean things on her science fair poster. Kate's use of science to solve the mystery works well within the plot; one sequence explains how to dust for fingerprints with cocoa powder. Uninteresting science clip art doesn't add much artistic spice, but the included fruit-battery experiment (which requires equipment which might be present in the home) is a good choice. The series protagonist's obsession with author avatar Dr. Caroline is a throughline that's run its course.The science is interesting; the flat story is less so. (Fiction. 8-10)