At a difficult place in his marriage and career, a middle-aged man gets a shot at a do-over when he's transformed back into his 18-year-old body.

The story is about a bar owner that fights with an organized crime.

Ki Moo-Hyeok, a lawyer with a high winning rate, only cares about money. Due to a murder case at a high school which he deals with, his reputation as a lawyer hits rock bottom. To regain his good name as a lawyer, he sneaks into the high school and work as a temporary teacher. He tries to reveal a secret which the students have, and gets involved with Teacher Ha So-Hyun, a P.E. teacher who loves her students. They then face the students'secret.