The Yellow Cat Mystery — Ellery Queen Jr.

On vacation in Florida, Djuna meets a cat with a peculiar secret

Djuna steps off the bus and into the Florida heat, ready for a few weeks of slow-paced Southern living with his friend Tommy, whose father recently moved to Dolphin Beach. After spending the whole summer solving mysteries, Djuna is looking forward to some peace and quiet.
 
But trouble has a way of finding Djuna. While Tommy gives him a tour of the town, Djuna spies two men sneaking away from a strange black boat. Inspecting the ship, Djuna discovers that it has been freshly painted and that the name has recently been changed. Is it possible that smugglers are operating in Dolphin Beach? There is something about this boat that tells Djuna he's not on vacation anymore -- he's on an adventure.
 
Ellery Queen is one of the world's finest detectives, but his adventures are nothing compared to the Ellery Queen Jr. Mystery Stories. Join Queen's apprentice, Djuna, and his trusty Scottie, Champ, on adventures filled with danger, suspense, and thrills.
 
The Yellow Cat Mystery is the seventh book in the Ellery Queen Jr. Mystery Stories, but you may enjoy reading the series in any order.