Willie Carlin was born and raised in Derry. Joining the British Army in 1965, he was recruited by MI5 in 1974 (and later the Force Research Unit), to infiltrate Sinn F in. Over the next 11 years, he built up close contacts with Martin McGuinness and Mitchel McLaughlin, becoming one of Britain's most valuable long-term agents in Northern Ireland. However, as his own republican commitment increased, he began withholding information from MI5. His cover blown by his unstable handler in 1985, Carlin was told that the IRA was on its way to kill him and, an hour later, he and his family were extracted from Northern Ireland on Margaret Thatcher's private jet.