In the villages and on the mountains of County Tyrone, in the heartland of the Provisional IRA's most active Brigade, the golden rule is 'Hear nothing, see nothing, know nothing'. To collaborate with British Intelligence is to invite an inescapable death sentence. But there is word on the mountain that inside the Brigade there is a 'tout', an informer. He will be identified, interrogated, tortured, then hooded and shot. Gary Brennard, the MI5 field agent, and Parker, who runs the informer, have to protect their man at all costs: he is the critical asset to hold on to until the stakes are high enough... and if the innocent step into the crossfire, that's just bad luck.