The Master Key is an interactive variety show which the viewers get to determine the fate of the player. Each week, celebrities compete with one another and play various games in order to achieve victory. The viewers become "Watchers" and participate in the game as well. By the number of votes, each star receives special abilities. Who will be chosen by the Watchers and become the final winner? Week in and week out, the hosts and the guests sometimes cooperate and sometimes betray each other to win the battle of the brains. In this fierce battle, they will learn how to work as a team and how to be cunning and daring enough to taste victory. Tune in to The Master Key to observe this fierce competition that takes place in various places of Korea.