HEAR NOTHING. SEE NOTHING. KNOW NOTHING.

This is the ruthless motto in the Provisional IRA's most active brigade.

To collaborate with British Intelligence means certain death.

But there is a rumour that an informer is operating within the Brigade. When identified he will be ruthlessly interrogated, tortured, then shot.

The MI5 agents running the informer must protect their man at all costs: he is their most critical asset, and they must keep him in place, even if that means innocent people must die.