Detective Young Jin, from the regional investigation unit, has only one thing on her mind to solve as many criminal cases as possible as a way to atone for her friend's murder 19 years ago. Then one day, one of these criminal cases hits too close to home again. Her neighbor's son, Eun Ho, seems to have mysteriously fallen off the roof of a hotel and left in a coma. Ruled as an apparent suicide attempt by the authorities, Young Jin senses foul play and decides to take it upon herself to get to the bottom of it. With the help of Eun Ho's homeroom teacher, Sun Woo, they both begin to uncover that Eun Ho's injuries were no accident.