When high school teacher Na Aejoon shows up for work on an ordinary day, he never expects to bump into his favorite celebrity in the hallway. But when his school becomes a filming location for a show starring Choi Siyeol, his bias from the idol group A-One, that's exactly what happens! If that's not enough to give a fanboy a heart attack, Siyeol takes an interest in Aejoon and asks him to join the show as his "co-teacher." Desperate to keep his fan life a secret, Aejoon is forced to put his acting skills to the test, and not just on camera. But as he spends more and more time with Siyeol, the deception becomes harder to keep up. Not to mention, he might not be the only one keeping secrets…
是一部悬疑剧，讲述了在与外部隔绝的私立高中，7名学生收到“匿名书信”后八天时间里发生的神秘杀人事件。
人人都在追忆逝去的青春，希望重新回到十八岁的年纪，弥补当年的遗憾，完成未完成的事。可是对于现年三十岁的医生徐允在（孔侑 饰）而言，因为车祸而导致的灵魂互换，让他成了表面三十岁的大叔，内心却是十八岁的少年的事情，应该不是那么令人兴奋。 因为这次互换，徐允在实际上成为了高中生姜景俊（申原昊 饰），看着镜中陌生的脸，成为允在的景俊起初迫切想要找到回到真身的办法，可一时半会却找不到。于是景俊只得不安的开始了新生活，而他首先要面对的就是允在的未婚妻，也是自己老师的吉多兰（李珉廷 饰）。面对自己未婚夫性情的大变，让多兰很是不适应。而这还只是故事的开端……
在广播电台共事的三名女子原本过著平凡稳定的生活，翻天覆地的改变却突然来袭。眼见她们的爱情及事业摇摇欲坠，幸福的婚姻难道只是幻觉？
一名饭店礼宾员和一名童年受过心理创伤的精神科医生，在被卷入一起令人费解的当地命案后彼此真心相待的故事。
