Eleven-year-old John Egan has an unusual talent: he can tell when people are lying. John hopes that one day his gift will guarantee his entry into the Guinness Book of World Records. Until then, he must navigate the powerful and destructive undercurrents of his loving but fragile family. When John and his parents move to the council-flat slums of Dublin, John finds himself in a perilous world. Even his relationship with his mother, a bond that is peculiarly close begins to break down. Amid the confusion of shifting landscapes and loyalties, he can rely only on his ability to detect lies. But John's obsession for discerning the truth becomes a violent and frightening fixation.