Kim Yun hee who is disguised as his brother kim yoon shik is forced to take the mens only national exam when she is caught as a substitute in the exam venue by lee sun joon. Kim yoonhee and lee sun joon passes the exam and kim yoonhee enters the men only sungkyunkwan as her brother kim yoon shik. Kim Yoon shik and lee sun joon is allotted to the same dorm and has to share their dorm room with their senior moon jae shik. These three also become friendly with another senior Go young hwa under certain circumstances and become the jaegum quartet. The student president is determined to make their life a living hell. Meanwhile the king gives the quartet a secret order. The quartet's adventures at sungkyunkwan and how they fulfill king's secret order is featured in this drama. Funny bromance, romance, action, politics.. this drama has everything you want. The ending is.. what can i say? to know the ending, watch the drama!