Lee Geun-hu

Hye-jeong, a lonely young girl who has drifted away from her family and avoids personal relationships, works in a factory, lives in a shared apartment, and leads an insipid and meaningless existence until one night she discovers that she has become a ghost.

One day, 25 years ago, missing Chun-bae's letter is delivered to his cousin, Jjang-goo. The letter contains Chun-bae's lover, Bok-soon, and other people's letters. Jjang-goo finds Bok-soon to deliver the letter and meets class president Jang together. The three people recall their memories from 25 years ago, and eventually faced the person who sent the letter. Through that, the tangles begin to unravel.

Life is tough for Chol-Min - his mother died during labor, forcing him to grow up alonge with his stoic police officer father. However, Chol-Min lives a high-spirited life and roams around town with his own mutt, a half-bred police dog, making friends and enemies along the way.

A team of tenacious detectives study the minds of murderers at a time when Korea's first serial murders terrorized the nation. Based on true events.