Kris Wu is the best detective in all of Korea, but when he meets Kim Jihae who is accused of murdering the class president at her highschool his world is turned upside down. She claims to be not guilty but all evidence points at her. Will he be able to solve the crime or will the girl he vowed to protect end up in jail with no fault? 

Kim Jihae is the most popular girl at Seoul High. Until she is framed for the death of her classroom president. She keeps telling her lawyer and the prosecutor that she's innocent, but no one believes her. Not even her two brothers who love her so dearly. But when the detective in charge tells her he believes her she is shaken for the first time and slowly starts falling in love with him. Will she be able show she's not a little girl or will she lose him to someone more mature? 

"I promise to protect you no matter what." 

"Not being able to tell you I love you, because you'll only think I'm a child, do you know that I'm crying?"