Whispers is a novel by American suspense author Dean Koontz, originally published in 1980. It was the first of Koontz's novels to appear on the New York Times Bestsellers List, and is widely credited with launching his career as a best-selling author.
Hilary Thomas, a screenwriter living in Los Angeles, is attacked in her home by Bruno Frye, a mentally disturbed man whose vineyard in Napa Valley she recently visited. Frye tries to rape her, but Hilary gets the drop on him and forces him to leave at gunpoint. She calls the police, but Detective Tony Clemenza and his partner tell her that Frye has an airtight alibi... they called his home and he answered, proving that he couldn't have been anywhere near Los Angeles that night.
The next day Frye returns and attacks Hilary again, this time receiving several stab wounds for his trouble before escaping. She calls the police and once again meets with Clemenza and his partner, who tell her that Frye's body has been found and take her to the morgue to identify it. Afterward, Clemenza asks Hilary out, and the two begin a romantic relationship. They grow closer a few days later, after Clemenza's partner is killed.
Returning home from Clemenza's place, Hilary is once again attacked by Frye. Frye escapes just before Clemenza arrives, and Hilary tells him what happened. After some investigating, the two contact Frye's lawyer, Joshua Rhinehart. The three of them then seek out Frye's psychologist, who lets them listen to a tape recording of one of Frye's sessions. Frye talks about identical twins being born with cauls on their faces, and says he read somewhere that this was a sign of the Devil.
Through Frye's point of view, we learn that he's been killing women he believes are possessed by the spirit of his dead mother, who abused him horribly throughout his life. Each time he kills one, he believes that her spirit simply moves to a new body. Now he's fixated on Hilary as his mother's latest "host." He also believes that his father was the Devil, and that his own penis bears some sort of deformity that would reveal this fact to any woman he became intimate with.
Meanwhile, Hilary and Tony meet an elderly woman who's been getting monthly payments from Frye's family for years. She tells them that Leo, Frye's grandfather, used to frequent the brothel she once owned, and that Leo brought his daughter, Katherine, there to be cared for after he found out she was pregnant, concocting a cover story about an old friend whose baby Katherine planned to adopt. In reality, Leo molested Katherine, which was the true cause of his daughter's pregnancy.
Shortly after Leo's death, Katherine gave birth to identical twin boys. The twins were born with cauls on their faces, leading the mentally unstable Katherine to believe they were demons. In order to preserve her father's cover story about the adoption, she raised her sons as if they were one person. They were both called Bruno, and both were rewarded or punished for anything either one of them did. They were not allowed to refer to each other as "you" or “he,” only as “I.” Any deviation from this resulted in horrific abuse.
Finally, Hilary and Clemenza return to Frye's home, where he once again attacks them. He is killed during a struggle with Clemenza.