Cam Jansen: the First Day of School Mystery #22

by Marjorie Weinman Sharmat

Nate has that same unflappable detective energy as Cam, but he solves his mysteries through dogged legwork and logical deduction rather than photographic memory—it's like watching someone solve a puzzle by asking the right questions instead of having all the pieces memorized. You'll appreciate how Sharmat builds genuine puzzles that readers can actually solve alongside Nate, and the friendship dynamic between Nate and his sidekick has that same comfortable, practical chemistry you enjoyed between Cam and Eric.

by Mari Lu Robbins

Published in 1967, this is a mystery that unfolds more like an adventure—two kids running away from home end up living in the Metropolitan Museum of Art and stumble into a genuine historical puzzle. What makes it perfect for you is that it has Cam's observational sharpness but wrapped in a much richer, more atmospheric story where the mystery matters less than the journey of discovery and self-understanding the characters experience.

by Trenton Lee Stewart

This one escalates the mystery-solving game considerably—instead of one clever kid, you've got a team of four gifted children with different talents working together on a mystery that's genuinely complex and high-stakes. Stewart writes with the same page-turning clarity as Adler, but he trusts his readers with more intricate plotting and gives each character distinct problem-solving approaches, so you get to see multiple ways of being smart.

by Blue Balliett

Here's where I'm going to surprise you a little: this is a mystery wrapped inside an art heist wrapped inside a book that's genuinely beautiful to look at—Balliett includes illustrations and visual puzzles that are part of solving the mystery itself. It's still fundamentally a smart-kid-solves-crime story like Cam Jansen, but it treats the reader like they're capable of noticing things in pictures and text that matter, which feels like a natural next step in complexity.