This is what you hand a Wimpy Kid devotee when you want them to accidentally learn some history. Mac Barnett's series nails the sweet spot between silly and smart—the premise is absurd (kid spy for the Queen!), the illustrations keep pages turning, and somehow your child emerges knowing actual facts about the Crown Jewels and Cold War geography.

The one mild flag: some cartoon illustrations reference historical violence (Tower of London beheadings), which one parent found too intense for younger kids. In context, these are brief historical asides in cartoon style, not graphic or dwelled upon, but worth previewing if you have a particularly sensitive reader.

Otherwise, this is a win. Kids genuinely find it funny (not just 'educational funny'), it builds reading stamina without feeling like work, and the meta-humor of a real author claiming his childhood spy stories are true is clever enough to engage adults reading aloud. A solid, entertaining chapter book series that sneaks in learning while keeping kids hooked.