该剧讲述死守犯罪现场的黄金时间的112中心的成员们和撼动韩国的极其凶恶的网络犯罪中被称为“Dr. Fabre”的Dark Web背后的巨大的犯罪大鳄对抗的故事，是成员们和犯罪的第三次记录。
讲的是车祸中失去父母的三月，被母亲好友收养，寄住在泰辰家的故事。三月失去父母后，住在泰辰家，却一直乖巧懂事，懂事的让人心疼；泰辰想要对三月好却不知怎么表达，只能默默守护。
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…
《心里的声音》改编自赵石网络漫画，由河秉勋执导，李光洙、郑素敏、金大明等主演。乍看之下可能会觉得这只是一部以描绘日常生活为主题的作品，但其实里面的故事非常夸张和搞笑，绝对只会发生在漫画中。该剧先行在Naver cast播出十集、每集10分钟的先行版，之后在KBS 2TV电视台放送。
