On a busy shopping street in Venice an African street vendor is shot dead. Nobody knows the dead African and only by chance Brunetti and his assistant Vianello find the victim's accommodation. There they are shot at, but the valuable rough diamonds they find did not interest the killer. Moreover, Patta interferes in the murder case and forbids Brunetti from further investigations because it is international terrorism. But Brunetti continues his investigation secretly. On his way to a nurse who wants to tell him the identity of the dead man, the commissioner is attacked. When Patta learns of Brunetti's solo effort, he forces the commissioner to request his transfer. To Sicily...