A night watchman travels the streets on the outskirts of Vigàta until, stopping in front of the gate of a villa, he realizes that the lock has been forced open. Later, the young son of Adelina, the housekeeper of Commissioner Montalbano, is arrested, who immediately professes himself innocent. But something does not look right and the commissioner decides to extend the detention. The question being: what really happened in that house? In the same sleepy Sicilian, town a quiet and reserved young woman is brutally killed with a hammer. Her battered body is found in the municipal archives, where the girl usually worked. The irregularity is that the girl should not have been there at all that day, as the offices were closed for building renovation works. So what was she doing there? And how did the killer escape from the scene unnoticed with their clothes covered in blood? The investigations bring to light the victim's varied personality and multiple secret lives. One after the other, different characters come under suspicion, only later to be cleared due to new evidence in a game of continuous twists and turns. But the uncomfortable truth will eventually reveal itself and it may be not what you expected. Meanwhile, a Swedish film crew arrives causing much interest from the local people.

There are many intriguing stories running in parallel in this fascinating episode: 1. The town of Vigata is buzzing as the new filming location for a Swedish television series set in 1850 that tells of a ship from their country that landed in Sicily. In the production frenzy, the director asks the locals to track down movies and vintage photos to faithfully recreate the air of Vigata at that time. 2. Meanwhile, the engineer Ernesto Sabatello, rummaging in the attic of his house, discovers some super-8 films shot by his father between 1973 and 1978. But what is intriguing the detective is that these are always taken on the same day (27th March) and always the same scene outside a country house. On hearing the story, Montalbano decides to look into this mystery. Is there something deeper and darker waiting to be discovered? 3. In the school attended by the son of Augello, a frightening and incomprehensible attack is carried out. Two people with their faces covered burst into the institute, spreading terror among teachers and children and then launch a threatening and obscure declaration. An additional mystery to shed some light on that will eventually reveal a local cyber-bullying phenomenon.