10 people, who dream of having a perfect life, travel back in time to 1 year ago. They are able to reset their lives there, but mysterious cases take place that threatens their lives.
Ji Hyung-Joo (Lee Joon-Hyuk) is a veteran detective and he has 7 years of work experience. He gets an opportunity to travel one year into the past. He enjoys his life that has been reset, but he learns that people who have traveled back in time, like him, are involved in mysterious cases. He tries to reveal the truth behind that.
Shin Ga-Hyun (Nam Ji-Hyun) is a webcomic writer. She has published her popular webcomic series “Hidden Killer” for the past 3 years. Shin Ga-Hyun is a workaholic and sensitive perfectionist. One day, she has a sudden accident. The accident turns her life into hell. At this time, she receives a proposal to travel back in time, to one year ago. Shin Ga-Hyun resets her life, but she faces an unexpected case.
