Showing Pale Kings and Princes by Robert B. Parker

When a young journalist researching the cocaine trade in a small Massachusetts town is found murdered, private detective Spenser is called in to find out who is responsible. Wheaton isn't just any small town though - Spenser soon discovers it's one of the biggest cocaine distribution centres in the Northeast. But the local drugs cartel are not the only suspects - did the journalist get too close to the truth, or too close to the wife of a very jealous man?