Du Xiyao, a modern agent and medical genius, traveled through time to become the four-year-old granddaughter of the Duke of Zhen. She rescued a little boy who was poisoned in Dujiacun, but she didn't know that the boy was the future cold-faced regent Xiao Yan. In order to find medicinal materials to develop an antidote, and to establish her own power, she pretended to be ill and left the family at the age of five, and rose up secretly in the past ten years.
After returning to Beijing, she unexpectedly reunited with Xiao Yan, who was now the regent. The two got entangled several times. Xiao Yan recognized her as her savior and stalked and protected her tenderly ever since. The two joined hands to uncover the truth about the poisoning back then, and also faced the treacherous situation in the court together.
