To pay her parents' debt, Seowon sneaks into Ellen Corporation in disguise as a male secretary and works in the Vice President Kangjun's office. Seowon and Kangjun unknowingly fall for each other, and Kangjun's fiancée, Sera, and Director Dongjin also grow feelings for Seowon, making this relationship even more complicated. Can Seowon complete her mission successfully in this chaos?