The story begins in the 1960's and is set mainly in Ireland and the United States, twins, alike in some ways and very different in others.  One twin due to a very unhappy and negative childhood departs clandestinely at 16 for wherever life takes him.  He arrives in the United States and survives as best he can, however he can, until fate - and having crossed one too many dangerous people - he is forced to return to Ireland.  Murder ensues, but who is the murderer and who is the victim, that is the dilemma.  John Roche a taciturn and far too casual and disrespectful detective for the preference of his superiors has to be borne because he is just so good at what he does ... catching murderers.  He ends up involved and working with the State Security Forces and between them they solve the mystery and make Dublin a slightly less dangerous place - at least for some people.