Fish You Were Here: Book 4 — Colleen A.F. Venable

The animals in Mr. Venezi's pet shop are used to how forgetful he is. Then he hires the perfect assistant, Viola. She does her job so well that Mr. V hardly needs to be there. In fact, one day, Mr. V doesn't come back at all! But then Viola starts ignoring the animals. Has Mr. V given the pet shop to a villain? Or is some other mystery afoot? Sasspants, PI(G) -- fluffy-but-determined guinea pig detective -- and junior detective Hamisher the hamster -- will soon fish out the answers!