Blitz (2011) on Netflix

In London, the violent Detective Sergeant Tom Brant is in trouble with the press and his superiors request a low profile attitude from him. When a cop killer called Blitz attacks police officers in London, Brant is assigned to the manhunt with his chief, the gay cop Porter Nash. His investigation shows that the criminal is the hoodlum Barry Weiss, but the police can not find any evidence against Barry. When he is released from jail thanks to his lawyer, Brant and Nash put Barry under surveillance expecting a new attack of the Blitz.