Proof of Innocence (2016)

Once a good cop, Pil-jae (Myung-min Kim) now uses his knowledge and skills to act as a "broker" between criminals and his lawyer boss Pan-su (Dong-il Sung). One day a mysterious letter from a prisoner on death row grabs his attention. As Pil-jae investigates into the case for his own benefit, it becomes soon apparent that he would be dealing with a murder case linked to the powerful Dai-hai corporation and its ruthless leader "The Madame".