The Attorney General of the United States has been assassinated at the intersection of 10th Street and Pennsylvania Avenue in Washington, DC.
As the investigation gets underway, there is fight between the FBI and the Metropolitan Police Department as to which agency would take the lead in the case. Ultimately, the decision is that the DC police should be in charge of the matter.
A former FBI agent -- now a DC police lieutenant -- is placed in charge of the case. Meanwhile there's an attempt from high levels within the FBI to undermine his investigation.
As the case progresses, police discover connections with a prostitute, foreign diplomats, and a former high-ranking government official.