Baek Ho Rang (Jung Da Bin) is the most popular girl in high school. Everybody wants to be her friend, and all of the boys dream of winning her heart. Although she is famously aloof, she is also a star on social media – with the whole school seemingly following her every post. But when a mysterious individual arrives online, she is caught off-guard. This person seems to know all of Baek Ho Rang’s deepest secrets, and is seemingly armed with all sorts of information about her that she’d rather was kept a secret forever! Desperate for answers, she seeks out the help of Go Eun Taek (Hwang Min Hyun), the meticulous, right-minded head of the school’s broadcasting club. However, in order to gain his assistance, she discovers that she will have to become a regular club member – a fact that eventually brings her together with a group of students she never thought she’d consider friends. Can she solve the mystery of the online poster? And could joining the club eventually lead to romance?