This is the smart kid mystery that doesn't talk down to its audience. Blue Balliett weaves Frank Lloyd Wright's actual Robie House into a puzzle-filled adventure that makes architecture feel urgent and cool—no small feat.

The pentomino puzzles scattered throughout are a clever touch that invites hands-on engagement (some kids will want to buy their own set). The friend dynamics are realistic: when Tommy returns, the established Petra-Calder duo gets complicated in ways that feel true to middle school.

It's dense enough that reluctant readers might bounce off, but for kids who like their mysteries with layers—coded messages, literary references, historical details—this delivers. The 4.7 Amazon rating and consistent 10+ age recommendations across sources suggest it's found its audience. Not a must-read for every kid, but a strong pick for the right one.