An unidentified body is discovered in New York City, with numbers and symbols written in blood near the corpse. Gilmo, a North Korean national who interprets the world through numbers, formulas and mathematical theories, is arrested on the spot. He used to have a quiet life back in Pyongyang. But when his father, a preeminent doctor, is discovered to be a secret Christian, he is subsequently incarcerated in a political prison overseen by a harsh, cruel warden. There, Gilmo meets the spirited Yeong-ae, who becomes his only friend. When Yeong-ae manages to escape, Gilmo flees to track her down. He uses his peculiar gifts to navigate betrayal and the criminal underworld of east Asia --- a world wholly alien to everything he's ever known.