Caleb Cleveland, Kid Cop

Caleb Cleveland, Kid Cop is a series of juvenile mystery novels that exists in-universe.

History
Angus McDonald frequently reads them and gifts them, describing them as having been very formative for him.

Luca, a priest of Istus in Refuge, is also seen enjoying one of them.

Trivia

 * Likely inspired by real-life child detective series such as Encyclopedia Brown (which Taako at one point references by calling Angus by that moniker) and Nancy Drew.
 * It is an allusion to a three-part literary masterpiece written by an elementary school aged Griffin, called "Grant Andrews: Kid Cop." Griffin and his brothers have mentioned Grant Andrews several times on their flagship podcast, "My Brother, My Brother and Me."