Dagyeong, an elite organization member belatedly found out the death of her boss who she served like her mother. After knowing that it was 'Chairman Lee''s doing, there's nothing she hasn't do to avenge him. However, it wasn't easy to approach him who has a 'Private Group' behind him. Just when Dagyeong was about to give up on everything, she get information about 'Chairman Lee' having a son who attends Chaebol High. 'Dagyeong', who risks her life for her last mission, infiltrates Cheabol High...