New revelations about the Northern Ireland conflict from a leading team of investigative journalists. Episode five traces how unionist anger grew as IRA attacks on the security forces killed members of their community. When Margaret Thatcher signed the Anglo-Irish Agreement in 1985, giving the Republic of Ireland political influence in the North, the anger spilled over into talk of insurrection. The programme reveals how loyalist groups rearmed and used intelligence leaks from soldiers and police to boost their campaign of killing, including new information about MI5 agents operating inside the largest loyalist group, the Ulster Defence Association.