Cheng Yao, the eldest daughter of the Cheng family, is forced to marry in her younger sister's place and become the Princess Consort of Prince Yu, Yu Jin. In the prince's residence, she uses her medical skills and intelligence to overcome one crisis after another, and gradually develops feelings for Yu Jin. But Yu Jin mistakenly believes she's a spy and puts her through a series of tests and torments. After learning the truth, Cheng Yao decides to leave the residence. Yu Jin realizes his mistake and begins a long, arduous pursuit to win her back.
