An unidentified body is discovered in New York City, with numbers and symbols written in blood near the corpse. Ahn Gil­mo, a North Korean national who interprets the world through numbers, formulas, and mathematical theories, is arrested on the spot. Previously incarcerated in a Korean political prison because his father was a secret Christian, Gilmo must now use his peculiar gifts to navigate the criminal world as he searches for the only family he has left. Angela, a CIA operative, is assigned to gain his trust and access his unique thought-process.