Detective Chun Jae-In goes undercover as high school student to befriend Seung-Hee , the teenage daughter of a powerful crime boss, but, Chun Jae-In doesn't remember high school being this hard. Not only does
Seung-Hee give Jae-In the cold shoulder, but Jae-In finds the math problems incredibly difficult and she has to deal with the school bullies. Meanwhile, handsome student No-Young enters the picture and Jae-In finds herself falling for him!
