Mike Boyle, a behavioural psychologist, heading a research team and drifting towards marrying Anna is suddenly confronted with a version of his father's past that he doesn't recognize. He is told that his late father, Brendan, had been a leading figure in the IRA and he is asked to be of service himself. Despite not being convinced that his father could ever have been involved with such an organization, Mike feels impelled to search for the truth. To facilitate his search he pretends to go along with the request to help the organization recoup jewellery that was stolen thirty years previously. Mike rapidly finds himself being manipulated by events over which he has little control with both British Intelligence and the IRA seeing him as their man. He treads a difficult and dangerous path which takes him from Liverpool to Ireland and Lake Garda in Italy before events reach a climax in Donegal.