When a miserly spinster is found brutally murdered in her Venice apartment, police immediately suspect her Romanian housekeeper. They are certain their job is done after the immigrant dies while fleeing arrest, but weeks later; a neighbor comes forward to defend the innocence of the accused. The only investigator who believes the alibi is Brunetti, who will have to go behind the backs of his superiors to vindicate the Romanian and find her employer's actual killer.

As always, the indispensable hacking skills of the ever-loyal Signorina Elettra are the perfect complement to Brunetti's meticulous detective work. She discovers mysterious deposits in the old woman's bank account, but who made them? As Brunetti investigates, his wife, at home, reads him teachings on the Seven Deadly Sins.