When important information is leaked from inside the Venetian Questura, Commissario Guido Brunetti is entrusted with the task of uncovering which of his colleagues is responsible. But before Brunetti can begin his investigation, he is surprised by the appearance in his office of a friend of his wife’s, who is fearful that her son is using drugs. A few weeks later, Tullio Gasparini, the woman’s husband, is found unconscious with a serious head injury at the foot of a bridge, and Brunetti is drawn to pursue a possible connection to the boy’s behaviour. But the truth is not straightforward. Following various contradictory leads, Brunetti navigates his way through a world of mysterious informant