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.

A desperate 35 year-old Young-sil is more than ready for full time job. And finally she gets a call from National security department as an intern. But her joy lasts no long, soon asked to leave. Accidently she discovers a secret about her boss and she suggest a deal of full time job to help him; secret spy.