Friends in High Places is the 9th in Donna Leon'sGuido Brunetti series of murder mystery / police procedurals set in Venice. The book appears to be out of print in the U.S., but is readily available in its British edition via several Amazon merchants.
As with most of the Brunetti series, the story has much to do with government corruption. In this case the means of corruption is Venetian real estate, and the outcome is murder. There is also a significant drug connection, leading to the death of one addict, and indirectly leading to the deaths of 2 others.
This is one of the best in the Brunetti series, and the series is among the best I've read. Leon has great sympathy for the crime- and corruption victims, as well as for those honest policemen who investigate the crimes. The characters in this novel, and in the series generally, are not just believable, but fully fleshed-out, unlike the stick-figures in many of the crime novels I've been reading lately.
There are no neat endings in any of the Brunetti novels. Justice is always thwarted, at least to some extent. Brunetti always solves the case, but the people in 'high places' always win in the end. Such is the case in this novel as well, though in this case Brunetti finds a way to make Italian reality work for rather than against justice.