(NOTE: The Book cover may vary if published by different companies.)

Author:   Enid Blyton

Categories:  English , Fiction , Mystery

Pages: 

Publisher: local

Cover: Softcover

Book description :

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.