The film opens with an Orange walk on The Twelfth, and an audio tape being handed to Paul Sullivan, an American human rights lawyer and activist, which becomes his death warrant. The film begins with a quote from Margaret Thatcher insisting that Northern Ireland is part of Britain. It ends with one from a former British intelligence agent, stating, "There are two laws running this country: one for the security forces and the other for the rest of us." UK mainland police investigator Peter Kerrigan, with the help of Sullivan's assistant, Ingrid Jessner, investigates the shooting death of Sullivan and his Provisional IRA driver by security forces in Northern Ireland. The investigation reveals the men were killed without warning. Captain Harris, an ex-army intelligence officer now in hiding, possesses a tape recording of senior military leaders and Conservative Party politicians discussing how they arranged the rise to power of Margaret Thatcher. Harris gives a copy of the tape to Jessner, after which British security forces kill Harris and blame his death on the IRA. Kerrigan is blackmailed into silence. Jessner has the tape, but without Harris to authenticate it, the recording can be dismissed as a forgery.
Background
The story references the dictatorship of General Augusto Pinochet in Chile, implying that British rule of Northern Ireland was sustained with terrorism equivalent to that which Pinochet inflicted upon his enemies; that the political ascent of Margaret Thatcher was like that of Pinochet, by means of a U.S.-sponsored coup d’état, not an election; and that police and right-wing politicians, who denounced the IRA as terrorists, were, themselves, engaged in state-sponsored terrorism. The implication that British state authorities are terrorists is reinforced with a scene in an Irish republican club of a singer singing a Wolfe Tones ballad honouring the H-Block hunger striker Joe McDonnell, including the chorus: The story of Hidden Agenda was inspired by the investigation into the Royal Ulster Constabulary's shoot-to-kill policy. The Peter Kerrigan character represents John Stalker, the leader of that investigation. The secret unit E4A of the Royal Ulster Constabulary, which was believed involved in the assassinations, is briefly mentioned. The Captain Harris character represents Colin Wallace, who was a technical advisor to the film. The Chief Constable Brody character represents RUC Chief Constable Sir John Hermon. The right-wing Tory conspirators Andrew Neame and member of British Intelligence Alec Nevin claim Airey Neave was involved in similar intrigues during the 1970s. All three of these characters have the initials A.N although Airey Neave was killed in 1979 while the conspiracy in question was in 1974. In conversation with Kerrigan, a conspirator justifies breaking the law to fight terrorism, by citing the use of force to extort confessions from the Birmingham Six. At one point, Teresa Doyle shows Jessnser a photograph of a masked British soldier posing with an IRA cadaver after a cross-border operation into the Irish Republic, representing a rumour that Captain Robert Nairac had such a trophy photograph of the body of John Francis Green.
Hidden Agenda was praised for its honesty and complexity, as well as its resonance. It was criticised for a simplistic view of the Northern Ireland Troubles as an anti-colonial war and for portraying the Troubles as an adjunct to British rather than Irish politics. Rotten Tomatoes retrospectively collected 18 reviews and gave the film a score of 83%.
