When Patty and Jo Faraday returned to Harker's Cove, the scene of their exciting adventure with an escaped convict, it was for a fun-filled summer vacation. It started with a birthday party at which the Faraday twins received a lovely music box with a toy drummer on top. But the toy drummer had a strange history, and one day he disappeared. How Patty and Jo caught a mysterious prowler and found out what the toy drummer really is makes exciting reading.