The Case of the Buried Treasure

Rue Cyprus and her Golden Retriever puppy, Kasey, embark on a summer break full of adventure and fun, but when Rue's parents take her on vacation, they meet Mrs. MacIntyre and her dog, who live at the beach full-time.
Rue strikes up a friendship with the lonely older woman and offers to take Rufus, her dog, to the beach with her family so he can do what he loves best - dig. Unfortunately, Mrs. MacIntyre discovers that $500 is missing from her cabin and she has no idea where it might have gone. Rue suspects she might know, but how do you question a suspect when the suspect can only say, "Ruff"?
Can Rue and Kasey find the money before the summer ends?