Revival by Stephen King is almost an homage to the classic Horror genre authors who dared test the boundaries of true darkness --- writers like Poe, H.R. James, Blackwood, and Lovecraft.
But most especially, Revival is a modern echo of the Arthur Machen classic, The Great God Pan, about a woman who undergoes a brain surgery experiment and then dies after glimpsing the monstrous shadow world of evil she is suddenly able to see.
The King novel revolves around another obsessive experimenter with the healing force of electrical shock therapy --- the one-time minister Charles Jacobs. The story is narrated by Jamie Morton, who was a child the first time he encountered Jacobs. Over the decades, the two of them reconnect intermittently. Jacobs becomes a carny show healer, whose fame grows as he appears to evoke miraculous cures with his secret electrical therapy inventions.
But the cures Jacobs provides may have horrifying after-effects for his subjects. As he ages in later years, Jacobs persists in his research nevertheless, pushing ever closer toward the ultimate boundary of revival from death itself.
Revival is one of the darkest novels in all of Stephen King's Horror fiction. It's closest precursor would be the grotesque Pet Sematary. The novel builds slowly to a truly hideous climax and the blackest of visions about human mortality. Even seasoned Horror fiction readers may close the last pages of this tale with an involuntary shudder.