From the back cover: "In the idyllic West Indies Lisa begins to piece her shattered life together. The beach and the sea wash away the searing memory of the car crash that killed her family. The brutal past fades - until she meets her dead husband's double... This is just the beginning of a spine-chilling plunge into the deadly icy depths beneath the island paradise. As Lisa sleepwalks closer to the truth she is pulled into a whirlpool of scientific sadism and mania - AND WHEN SHE WAKES SCREAMING IT WILL BE TOO LATE! CHILLER - the knife-edge novel which merges horror and science fiction in a brain-freezing rush of psychoterror!"
I really enjoyed this book. It reminded me in parts of The Island Of Dr. Moreau and Tender Is The Flesh (trigger warning for SA however). Surprisingly, I am the first person to leave a rating for Chiller on Goodreads, the book is only 43 years old... Also, the cover artwork is excellent, the artist is not credited though.