The true story of a strange, lost film. In 1972, the IRA allowed an unusual documentary crew to film its members carrying out attacks. Right at the bloodiest point of the Northern Ireland conflict, IRA bombers were filmed unmasked, and most of its underground leadership appeared on camera. The film looked like a propaganda coup, before disappearing and going largely unseen for almost 50 years, with the IRA never allowing anything like it to happen again. The unearthing of the film sets Darragh MacIntyre off in search of the men who made it, the bombers who willingly showed their faces on camera, and the reason for its disappearance. In doing so, he finds himself following the footprints of spies.