This is what good YA mystery looks like. Maureen Johnson respects her readers' intelligence with a genuinely intricate plot that doesn't dumb things down. The dual-timeline structure is ambitious and actually works, the boarding school setting is atmospheric without being cliché, and Stevie Bell is the kind of protagonist who makes kids want to be smarter.
The crime content is real—kidnapping, murder, death—but handled with restraint. It's dark enough to feel legitimate but not so graphic that you'll regret handing it to your 12-year-old. Some cursing, some teenage relationship stuff, nothing that'll shock anyone who's been in a middle school hallway.
The real win here is that it's actually entertaining. This isn't vegetables disguised as dessert—it's a legitimately engaging mystery that happens to build critical thinking skills. Kids who claim they hate reading will burn through this series. Fair warning: it ends on a cliffhanger, so budget for books 2 and 3.