On an extended holiday in London, Dr. Tom Sutherland befriends a mysterious surgeon named Nordhagen and begins a wild affair with the doctor's exotic assistant, Lina. Seduced and completely enthralled by Lina, Tom can think only of being with her, following her deeper into forbidden fantasies and dark pleasures. But fantasy turns to nightmare when Tom discovers the basement laboratory of Dr. Nordhagen, a secret chamber where cruelty, desire and madness combine to form the ultimate evil.