The series tells the story of Yun Weishan (played by Esther Yu), a spy longing for freedom, who infiltrates the palace to complete a mission. Within the eerie and mysterious palace, she encounters love and friendship, embarks on a journey of self-discovery, and finds the determination to move forward. Together with the rebellious nobleman Gong Ziyu (played by Zhang Linghe), they grow and mature through their shared experiences.