Harry Potter and the Prisoner of Azkaban
by J. K. Rowling
Middle grade · ages 9–12 · 880L (~5th grade) · 2015
Why we'd hand it over
The tonal and structural leap from books 1–2: darker, more layered, and the first book where the mystery is genuinely unsolvable until the final reveal — kids feel genuinely unmoored, which is precisely the point.