From the back of the book
When Philip, Dinah, Lucy-Ann and Jack spend their holidays on a remote stretch of the Cornish coast, they are soon embroiled in a thrilling mystery. They discover secret passages and ancient mines, hear mysterious noises, and see unexplained lights on the cliffs at night. Everything seems to point to the desolate Isle of Gloom. Only there will they get to the bottom of the mystery- if they dare! Do you dare help the Adventure Squad investigate the Isle of Gloom? With your help they might foil a sinister scheme. But tread carefully. If you make the wrong choices, the intrepid adventurers could be in deadly peril.