Prince of the City is a 1981 American neo-noir crime drama film directed and co-written by Sidney Lumet. The film follows Daniel Ciello, an officer of the New York Police Department who chooses, for idealistic reasons, to expose corruption in the force. Ciello, played by Treat Williams, was based on the NYPD narcotics detective Robert Leuci. The film's large supporting cast also features Jerry Orbach, Bob Balaban, and Lindsay Crouse. The screenplay, by Lumet and Jay Presson Allen, is based on Robert Daley's 1978 book of the same name, and was nominated for an Academy Award for Best Adapted Screenplay. Plot Danny Ciello is a narcotics detective who works in the Special Investigative Unit (SIU) of the New York Police Department. He and his partners are called "Princes of the City" because they are largely unsupervised and are given wide latitude to make cases against defendants. They are involved in numerous illegal practices, such as skimming money from criminals, and supplying informants with drugs. Danny has a drug-addict brother and a cousin in organized crime. After an incident in which Danny beats up a junkie to supply another junkie with heroin, his conscience begins to bother him. He is approached by internal affairs and federal prosecutors to participate in an investigation into police corruption. In exchange for potentially avoiding prosecution and gaining federal protection for himself and his family, Ciello wears a wire and goes undercover to expose the inner workings of illegal police activity and corruption. He agrees to cooperate as long as he does not have to turn in his partners, but his past misdeeds and criminal associates come back to haunt him. One of his partners commits suicide during interrogation, and his cousin in the Mafia, who saves Danny's life on one occasion and warns him of a contract on his life on another, winds up dead. While confessing to three crimes he committed in the 11 years he worked for the SIU, Danny perjures himself by denying the many other offenses he and his partners have committed. Despite repeatedly professing loyalty, Danny finally gives up all of his partners, one of whom shoots himself as a result of this betrayal. Most of the others turn against him. In the end, the chief government prosecutor decides not to prosecute Danny, and he returns to work as an instructor at the Police Academy. Cast Treat Williams as Daniel