Ireland. Early 1980s. British Intelligence seek to penetrate the leadership of the IRA. Through his burgeoning relationship with a Belfast university lecturer, herself a British agent, a choirmaster from Derry is identified as a possible candidate. The relationship between these two, inspired by their shared passion for music, is encouraged and shadowed by British Intelligence.
Beset by conflicting loyalties, each wants to protect the other. Each has to confront the dilemma of betrayal – the machinery by which the intelligence services operate.