Author - Enid Blyton
Publisher -  Pan MacMillan
Edition - 2006
Binding - Paperback
Language - English
Pages - 260
Condition - Used

What is the secret of the old castle on the hill, and why are the locals so afraid of it? When flashing lights are seen in a distant tower, Philip, Dinah, Lucy-Ann, and Jack decide to investigate—and discover a very sinister plot concealed within its hidden rooms and gloomy underground passages.