Popular gag-man Yoon Se-yoon suddenly started to show strange behaviors, such as repeating weird movements or spitting unknown words one day when he was 14 - The behavior gradually disappeared, but it still remains a terrible memory for his family and acquaintances who witnessed him at that time. Then one day, Se-yoon who is now a head of a family hears an unidentified sound once again. That thing starts to bother him more and more - The 15-day record surrounding popular comedian Yoo Se-yoon. In December, the shocking identity of 'the thing' is revealed.