After losing his only son, Old Kim establishes Haksagol, an all-male boarding house. Admission requires a strict exam and interview, and anyone who breaks its ten rules—such as bans on drinking or protests—is immediately expelled. This year’s top entrant, Jin-young, is secretly a female law student disguised as a man. As she struggles to hide her identity, unforeseen events begin to shake the foundations of Haksagol.