Stuart Gibbs

Belly Up opens with the killing of a hippopotamus at a theme park zoo and a twelve-year-old boy investigating it, which is precisely as funny as intended. Gibbs runs several mystery series for children, including Spy School and Moon Base Alpha, and wrote for Hollywood first, on animated features among other things. He researches the settings properly, so the zoo procedure and the tradecraft are close enough to real that the jokes have something solid to stand on.