Shamrock, a notorious figure often described as an assassin, has become a guardian of justice in Northern Ireland in the turbulent days before the Good Friday agreement. He confronts a splinter group of "the real IRA" which has targeted a charismatic female member of Parliament. A Special Branch investigator attempts to unravel the mystery of Shamrock, while protecting the MP. A bookish man attending a reading conference and three American women on holiday are drawn into contact with the conflict that has emerged between Shamrock, the British detective, and the agitators who seek to disrupt the peace agreement.