Relentless.

About Relentless

Dean Ray Koontz is an American author. His novels are billed as suspense thrillers, but frequently incorporate elements of horror, fantasy, science fiction, mystery, and satire. Many of his books have appeared on The New York Times Best Seller list, with fourteen hardcovers and sixteen paperbacks reaching the number-one position. Koontz wrote under a number of pen names earlier in his career, including "David Axton", "Deanna Dwyer", "K. R. Dwyer", "Leigh Nichols" and "Brian Coffey". He has published over 105 novels and a number of novellas and collections of short stories, and has sold over 500 million copies of his work. He has been acknowledged as "America's most popular suspense novelist" by Rolling Stone and as one of today's most celebrated and successful writers.