Nocturnal: Min-tae, a once-notorious gangster who now leads a peaceful retired life, discovers the bloody corpse of his only next of kin: his younger brother Seok-tae. With his brother’s missing wife Moon-young as the prime suspect, Min-tae uncovers a suspicious last phone call between her and a mysterious novelist, sparking a vicious hunt for the truth despite his seemingly deceitful former crime syndicate and the police in hot pursuit.