'The boy turned and looked at me, and everything slowed right down...In that moment, there was nothing but me and our boy, our eyes holding each other's. Dillon.' Five years ago, three-year-old Dillon disappeared. For his father Harry - who left him alone for ten crucial minutes - it was an unforgivable lapse. Yet Dillon's mother Robin has never blamed her husband: her own secret guilt is burden enough. Now they're trying to move on, returning home to Dublin to make a fresh start. But their lives are turned upside down the day Harry sees an eight-year-old boy in the crowd. A boy Harry is convinced is Dillon. But the boy vanishes before he can do anything about it. What Harry thought he saw quickly plunges their marriage into a spiral of crazed obsession and broken trust, uncovering deceits and shameful secrets. Everything Robyn and Harry ever believed in one another is cast into doubt. And at the centre of it all is the boy that never was...