The Monster of Florence by Douglas Preston and Mario Spezi is far from dissatisfying. This is truly Donna Leone meets Franz Kafka. The two journalists who pursued the identity of the Monster, a serial killer who preyed on young couples spooning in the hills around the city, became a part of the story, so much a part of the story that Preston was indicted and Spezi was jailed and accused of being the Monster.
These ludicrous accusations were made because Spezi and Preston were too successful in their pursuit of the Monster. Their discoveries put the lie to the official line of inquiry, to which the entire Italian justice system was committed despite its depending on Satanic cults, mentally retarded and psychotic "witnesses," and a conspiracy that included a quarter of the population of Tuscany from peasants to the nobility.
My favorite line of official reasoning was the theory that the bad guys wanted it to look as though a doctor who had been murdered had really committed suicide by drowning himself. So the murderers exchanged his corpse with the body of another man who really had drowned. Well, this leads to a lot of questions but it's been done, and I suspect it's been done in Italy rather more often than in, say, Wales.
However, when an exhumation is done 17 years after the burial, the doctor is found in the grave where the other guy had been buried, and what's more he is found to have been murdered. The police and district attorney-equivalent believe that the bad guys, anticipating the possibility that their substitution might be brought to light, switched the bodies again. The doctor's body (we have no clue where it's been for the last 17 years) was now placed in the grave and the body of the mysterious other man was spirited away. Unlikely as this story seems, the justice system holds firmly to it and argues its likelihood with a straight face.
It gets worse. Much worse. The story is mesmerizing. There's the antique Tuscan doorstop that's used to communicate with the underworld. There's the old .22 pistol used in every one of the murders along with cartridges from the same old box. There's the Sardinian tough guy who is thought to have murdered his wife. There's incest, sex games, clouds of questionable witnesses, a tremendous amount of unnecessary official secrecy, complicated family dynamics that put ancient Rome to shame, and the story of the filming of the movie from Tom Harris' book, Hannibal Rising (the character was based on the Monster) in the pallazo of a thoroughly charming Italian count. And a great deal more.