A Refiner's Fire by Donna Leon

About Brunetti returns with a gripping and powerful case about the murkiness of power and a test of loyaltiesWhen two teenage gangs are arrested after clashing violently in one of Venice's campi, the son of a local hero is implicated. But when Commissario Guido Brunetti is asked by a wealthy foreigner to vet this man, Monforte, for a job, he discovers that Monforte might not be such a hero after all.This seeming contradiction, and a brutal attack on one of Brunetti's colleagues by a possible gang member, concentrate Brunetti's attentions. Soon, he discovers the sordid hypocrisy surrounding Monforte's past, culminating in a fiery meeting of two gangs and a final opportunity for redemption.A Refiner's Fire is Donna Leon at her very best- an elegant, sophisticated storyteller whose indelible characters become richer with each book, and who constantly interrogates the ambiguity between moral and legal justice.