The Island of Adventure (Adventure Series)

The first thrilling installment in Enid Blyton's Adventure series For Philip, Dinah, Lucy-Ann, Jack, and Kiki the parrot, the summer holidays in Cornwall are everything they'd hoped for, until they begin to realize that something very sinister is taking place on the mysterious Isle of Gloom—where a dangerous adventure awaits them in the abandoned copper mines and secret tunnels beneath the sea.