Commissario Soneri, a Parma police officer and gourmet, is investigating an unsolved case of a dead body found in the River Po. His colleagues at the time couldn’t decide if it was a suicide or a murder, nor could they establish the victim’s identity. To close the case, Soneri needs to look a little further. It’s just a formality, a matter of going through the motions. Soneri, however, is not one for formalities. He can’t endure burying a person without a name, so he decides to reopen the case. Soneri, an intelligent and apparently grouchy man, uses unconventional policing methods. His partner, Angela Cornelio, is a lawyer and helps him with his enquiries.
The investigation leads them to river life, where he tries to break the wall of silence, typical of small communities harbouring poachers, petty criminals and profiteers - even a monster in the waters of the River Po. Soneri realises that the fog surrounding the Po makes things invisible and people unseen; it changes their identities; it deceives. And sometimes it kills.