When doubts arise about a five-year-old murder conviction, a veteran detective partners with a young hotshot to hunt down the case's hidden truths.

One day, during a university festival where people are often known to find a partner, the 3 incredibly single members of the robot club decide to attend. There the sloppy and timid Hwi-so meets a very aggressive girl by the name of Hye-jin. His romantic advances, which he learned through reading books and watching YouTube, finally wake up to make their move. But will two finally become one this fall?

Drama tells the story of Ko Dong-Man and Choi Ae-Ra. In their school days, Ko Dong-Man took part in taekwondo. Now, he makes a living by working as a contract employee and also goes after the UFC title. Choi Ae-Ra hoped to become an announcer, but she gave up her dream. Now, she works at the information desk of a department store.

Park Cha O Reum works as a rookie judge. She is in her mid-20's and follows "an eye for an eye" principle. She does not accept prejudice or blindly follow authority. Dealing with cases, she and her colleagues, including Im Ba-Reun, grow as persons.

Chun Jae In is an elite detective with a genius IQ, who guided by only facts, logic, and numbers. Meanwhile, Kim Dan is a rookie detective who can see ghosts. They work together to uncover a conspiracy involving a powerful organization.

The memory of their painful breakup still fresh in their minds, two former lovers reunite years later as a top actor and a documentary producer.