This drama is adapted from the manga of the same name by Asami Rito. It tells the story of a former police officer, Haruo Yamashita (Masaya Nakagawa), who was killed on Christmas Eve. His daughter Shinmugi Yamashita (Suzu Hirose) uses the letters left by her father as clues to track down the truth. The letter left by her father says "wrongful conviction". As they get closer to the truth of the incident, the two events of the present and the past are intricately intertwined...