The second exciting installment in Enid Blyton's Adventure series Why is everyone so afraid of the castle on the hill, and what dark secrets lurk inside its walls? Philip, Dinah, Lucy-Ann, Jack, and Kiki the parrot are on holiday in the countryside, staying on the side of Castle Hill. When flashing lights are seen in a distant tower, they decide to investigateand discover a very sinister plot concealed within its hidden rooms and gloomy underground passages.