King & Kayla and the Case of the Mysterious Mouse, Paperback/Dori Hillestad Butler

A lovable dog helps his human girl solve a mystery. King and Kayla are playing fetch with their friends, Jillian and Thor. Jillian throws King's favorite ball too hard, and now it's gone missing King and Kayla must put together the clues to figure out where it went--and who has it.