The Island of Adventure (Adventure Series)

For Philip, Dinah, Lucy-Ann and Jack, the holiday in Cornwall is everything they'd hope for - until they begin to realize that something very sinister is taking place on the mysterious Isle of Gloom. But they're not prepared for the dangerous adventure that awaits them in the abandoned copper mines and secret tunnels beneath the sea. Other titles in the series include: "The Castle of Adventure", "The Valley of Adventure", "The Sea of Adventure", "The Mountain of Adventure", "The Ship of Adventure", "The Circus of Adventure", and, "The River or Adventure".