On an autumn morning, Deborah Sheldon and her four children are savagely killed. Their murders worry the inhabitants and some of them could swear to have seen Paul Sheldon, the recently dead and buried father, wander in town. To clarify the situation, reporter Shelby Williams goes to Chesstomb, scene of the tragedy, to investigate. He discovers that Paul Sheldon grave has been ransacked and his body is missing.

Shortly after, Shelby learns a lot about the town’s past: its name comes from the massacre of a colony in the 19th century by two gang enemies Borrow Limeley and Finnegan Mower. They executed the families through a living game of chess. He meets Mr and Mrs Motherwell. They are haunted by their son’s death which circumstances were uncanny. And Joey Milton, who is the reference concerning the town history. He draws the attention of the reporter towards a house called Myseri, located in the outskirts of town, and its peculiar past. It just has been transmitted through inheritance to William Halsey by a distant relative, Albert, whose brother was a famous doctor in the city. Shelby tells about this story in a letter to his wife.

"Shortly after the succession, a strange and dreadful man, the old doctor Karl Graves, urgently offers William to buy his new house with everything in it, especially what is in the basement. Intrigued, William decides to go see the house for himself. When he arrives, he is the first one to enter the domain since 1920, after an express request from Albert Halsey. He discovers in the basement some medical equipment and a chest containing half a skull and vial full of a serum still luminescent. William suspects his relatives to have lead some vivisection experiments and tries to learn more about the story. The skull is philosopher René Descartes’, however he finds nothing about the vial."

Shelby is distracted in his researches when he finds an old journal, written by Charles Foster Wade. In it he describes events that happened in 1920 between Allan Halsey, Karl Graves, Herbert West, a rival practitioner. Wades also talks about his relationship with Lovecraft, a young writer, that grows into a friendship, and their encounter with Herbert West during a party hosted by Allan Halsey, dean of the Faculty of medicine. Wade and Lovecraft came as reporters and are really interested by West’s revelations: he would be in possession of a serum able to revitalise dead flesh. West offers them to witness the experiment in order to transcribe them later. In the basement of the house called Myseri that West bought for his works, the trio meets to lead dire experiments. One of them turns into a nightmare, killing Karl Grave’s lover. The journal ends with Allan Halsey’s death which happened during a quarrel involving a reanimation in West’s basement. A question remains unanswered, what is this serum?

Shelby Williams continues his investigation and more terrible things happen in Chesstomb. A terrifying invasion of violent reanimated corpses have the army involved. Documents prove how Karl Graves is behind this nightmare. Furthermore, he is the only one to know from where comes the serum but William Halsey finds the source despite himself. It comes from the blackish body of a frightening creature. He also discovers that his relative, Albert, had an affair with a young woman, Elisabeth Quincey. She has knowledge of the experiments in 1920 and knows how to destroy the thing that lays in the basement. This is Sharmat, a demon that legends tie to the time of Jesus Christ birth. Apocryphal texts describe it as the Christ evil twin, possessing the same powers of resurrection but reversed. William also finds out she has a daughter, Deborah, married to Paul Sheldon. After the tragic death of her family, Elisabeth understand she has no other choice than to go to Chesstomb to kill Sharmat. She knows that its goal is to unleash the Apocalypse and reanimate the dead. Calling to celestial forces, she destroys it, causing a storm that smashes half of the town.

The text ends with a last journal, one from Dr Nathanaël Crave, head of a psychiatric institution. In it, he describes the strange obsession of one of his patient for the game of chess, the white and black, and his taste for puns. His name is William Halsey, he is a writer and wrote a horror story about a city, Chesstomb. To make it more believable, he created a character after himself and called Shelby Williams, an anagram. When he is found hang in his room, Dr Crave finds in his belongings a curious vial full of a luminescent serum and the original manuscript of the book.