The protagonist, once an assistant manager on Daeyoung Corporation’s Spain team, is forced into a transfer to distribution after having their achievements stolen by superiors. There, He begins working as the personal secretary to Kang Mun-jeong, the only legitimate heir of the Daeyoung Group. Feeling her position threatened, Executive Director Kang Mun-jeong proposes a contract marriage to the protagonist, Yoon Tae-sik, who has served faithfully at her side for three years, in order to once again draw public attention to herself. The price of the marriage: 10 billion won. Thus begins an office drama, as the protagonist carries out the terms of this contract marriage, with 10 billion won on the line.