""Fred Vargas is an unusual and highly individual writer, with a style and tone all her own." "
Commissaire Adamsberg is worried about a series of panic attacks that he has experienced in recent days, triggered by subconscious memories that he cannot comprehend. By piecing together what he was doing when the attacks took place, Adamsberg realises what is triggering his memories. He becomes convinced that a serial killer, along with his trademark weapon, a trident fork, who has been killing since 1943, may have reappeared. A woman in Schiltigheim has been murdered in a similar manner, and as with the other cases, a man has confessed to the crime but has no recollection of the attack.
The Commissaire is convinced that the murders are the responsibility of Judge Fulgence, a character in his childhood who also tried to frame Adamsberg's brother for one of the murders. However, when a murder takes place in Quebec, where Adamsberg is on a temporary assignment, it is the policeman who now comes under suspicion for murder. In order to prove his innocence and find the supposedly deceased Judge Fulgence, Adamsberg must go on the run and use all of his wit to solve the cases.