From the creator and producers of Bodyguard, this "consistently thrilling" (Slate) drama returns as the internal affairs investigators of AC-12 face their most vicious adversary yet. Led by Superintendent Hastings (Adrian Dunbar, Blood), DI Kate Fleming (Vicky McClure, Broadchurch) and DS Steve Arnott (Martin Compston, The Great Train Robbery) probe the hijacking of a seized-drugs transport that left three officers dead. They suspect corrupt cops leaked information to John Corbett (Stephen Graham, Boardwalk Empire), a ruthless organized crime boss. When they learn that an undercover officer is embedded in Corbett's group, AC-12 come closer than ever to discovering the identity of the ringleader within the police department-but what they find could tear their team apart.