https://www.amazon.com/Inferno-Larry-Niven/dp/0765316765/ref=sr_1_1?ie=UTF8&qid=1536677127&sr=8-1&keywords=Inferno+niven
https://www.amazon.com/Escape-Hell-Inferno-Book-2-ebook/dp/B001QREWRS/ref=sr_1_2?ie=UTF8&qid=1536677147&sr=8-2&keywords=Inferno+niven
Ahhhh. Thanks. That explains my not remembering. I tend to avoid satanic themed writings and movies. Will consider making an exception with those.