It's a strange night for Paolo Torrigiani, who has been working for twenty years as night watchman in Lucca: after a violent argument with his colleague Alcide Catellota, he goes to look for him to try and make up, but finds his friend dead.
Catellota was shot in the stomach and now lies lifeless in a shoes factory. Paolo knows that factory very well, not only for professional duties but also for private reasons: the owner, Oscar Lecetti lives in that same place together with his beautiful Russian wife Nadia.
The woman has become Paolo's only reason to live after his wife Giulia left him one year earlier and he has been spending part of his shifts under Nadia's window in the hope of getting to know her.
That night, tragedy and fate are helpful to Paolo: he meets Nadia and finally has the opportunity to talk to her while they go in search of her husband, who is playing cards with some friends and still unaware of the event.
Nadia seems very upset and tells Paolo a confusing story .She talks of her brother Dimitri who doesn't know about Nadia's marriage and her life in Italy. Dimitri has spent the last five years in prison for a robbery and has never been informed about her sister. But now Dimitri is a free man again and Nadia has heard from her family that he's about to come to Italy: he apparently resents the fact he was never told about Nadia's new life.
The woman doesn't wish to reveal any of this to Oscar who, since they got married, has forced her to cut any possible contact with home - to the point of not allowing her to read books written in Russian.
Also, she now fears Dimitri might be involved in the murder, so she asks Paolo to protect her from her brother, should he ever turn up. lt's the beginning of a new life for Paolo, filled by the bizarre investigation into Dimitri's path and into Catellota's murder, and also by the frequent contacts he now has with the woman of his dreams. But as soon as Nadia realises the shy watchman has feelings for her, she stops meeting him.
However, Paolo’s investigation continues and he even starts suspecting his own colleagues, including his new partner who is now on night shifts with him because of the new regulations established after the murder. Paolo is now forced tobe accompanied by silent Salvatore Russo, who is obsessed by a jealous and self-destructive wife.
One night, after Salvatore has run home to calm his suicidal wife down, Paolo meets Dimitri. Everything is more confusing than ever and everyone involved seems to hide the real truth. The watchman feels alone in the heart of a mistery that nobody wants to unveil. And who shot Catellota that night?