The Cup of Thanatos — Charlotte Hunt

Dr. Paul Holton could no longer ignore the facts: the mystery-shrouded Thanatos Society had sprung up from the smouldering ashes of the evil "Circle of Ra" he had once helped to destroy. The name of the Satanist leader was different, but Paul recognized the familiar Machiavellic techniques. Once again the insidious Dr. Blackton was pandering to his all-consuming lust for power and world domination.

Suddenly Paul found himself deeply involved, for Sarah Wellington, a young and gentle friend, showed signs of drug addiction -- and Sarah wore around her neck the distinctive symbol of the Society, named in honor of Thanatos -- the ancient God of Death...

Paul had always known he and Dr. Blackton would meet again. He knew, too, that one mistake could plunge them all into the Kingdom of Darkness.